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1. am m UE 2 34 nj NJ _ mit dm Lil E ora m LU I d UL Lu E F afl m LET LENIN 111 1 GB of Memory Based on industry leading AMD Opteron microprocessors the HPC A5808 32 server provides industry leading scalable x64 processing with the latest I O network memory and power efficient technologies With features such as AMD quad core Opteron microprocessors and up to 256GB of DDR2 for memory intensive performance multithreaded applications like ERP e commerce and virtualization will see significant performance improvements And HPC MasterSight delivers features to help manage the system with inclusive diagnostic tools opecializing in High Performance Computers HPC systems Inc HPC Svstems Inc is a solution provider serving the financial health educational and eccles ose taie government sector We appreciate that you have a choice of 48009 Fremont Blvd dozens of vendors but not all of them have our uncompromising Fremont CA 94538 dedication and experience in producing the best solutions Tel 510 656 8282 ha Fax 510 656 8341 AMD SBA E mail info hpcsystems com ta ee AMD AMD Opteron and the AMD loge are registered trademarks of the Advanced Micro Dedos or its subsidiaries in the LIS and other countries letters DEMU BLUETOOT
2. 80 Cores starting at 33 900 QSOL COMI Server Appliances 800 933 7511 2007 QSOL COM INC All rights reserved all trademarks are the property of their respective companies GO SOLID INCREASE RELIABILTY solid state systems fully x86 compatible fanless quiet operation Direct Plug IDE Flash Modules Intel VIA amp AMD CPUs 95 Efficiency Rated PicoPSU Power Supplies DISCOVER MINI ITX oos SUPPLY www logicsupply com JOURNAL Editor in Chief Nick Petreley ljeditor linuxjournal com Executive Editor Senior Editor Art Director Products Editor Editor Emeritus Technical Editor Senior Columnist Chef Francais Security Editor Jill Franklin jillelinuxjournal com Doc Searls doc linuxjournal com Garrick Antikajian garrick linuxjournal com James Gray newproducts linuxjournal com Don Marti dmarti linuxjournal com Michael Baxter mab cruzio com Reuven Lerner reuvenGlerner co il Marcel Gagn mggagne salmar com Mick Bauer mick visi com Contributing Editors David A Bandel e Ibrahim Haddad Robert Love Zack Brown Dave Phillips Marco Fioretti e Ludovic Marcotte e Paul Barry Paul McKenney Dave Taylor Proofreader Geri Gale Publisher General Manager Director of Sales Regional Sales Manager Regional Sales Manager Circulation Director Marketing Coordinator System Administrator Webmaster Accountant Carlie
3. Figure 1 Adobe After Effects Interface but the prices run up to thousands of dollars per seat with extra costs for maintenance and render node licenses For those with smaller budgets Linux compositing has been perpetually out of reach unless one has the patience to do hand scripting in ImageMagick which is far more technical than most artists care to get and generally requires the addition of a hacker to the pipeline another cost point or work frame by frame in GIMP which is laborious and not worth the effort for any but the smallest projects Consequently the only budget friendly solutions for a small studio has been Adobe s After Effects or Apple s Motion which means adding a Windows or Mac OS machine to the pipeline Both are very capable useful tools that produce professional results but neither are open source The two classes of compositors are built around two divergent interface paradigms 88 november 2007 www linuxjournal com Open Source Compositing in me i pea which dramatically effect work flow The first of these paradigms is the Photoshop paradigm It shows up most prominently in After Effects and in a modified form in Apple Motion and works by marrying the interface conventions of Photoshop with a basic multitrack editor interface In this paradigm composites are achieved using lay ers of images built atop each other with each layer being operated upon by its own effects stack
4. Events can be used to tell the following if a new association has started or if an old one has terminated if a peer has changed state by say one of the interfaces becoming unavailable or a new interface becoming available if a send has failed a remote error has occurred or a remote peer has shut down if partial delivery has failed and if authentication information is available If an event is received in the event buffer first its type must be found and then the buffer can be cast to a suitable type for that event For example the code to handle a shutdown event is void handle_event void buf union Sctp notification notification struct sn_header head notification buf switch notification gt sn_header sn_type case SCTP_SHUTDOWN_EVENT struct sctp_shutdown_event shut shut struct sctp_shutdown_event buf printf Shutdown on assoc id d n shut gt sse_assoc_id break default printf Unhandled event type d n notification sn header sn type Closing an Association A socket can support multiple associations If you close a socket it closes all of the associations It is sometimes desirable to close only a single association but not the socket so that the socket can continue to be used for the other associations SCTP can abort an association or close it gracefully Graceful shut down will ensure that any queued messages are delivered properly before shutdown while abort does
5. If you don t do this mmapping will never work for writing to files Ii you don t know Tile size im advance as 15 often the case with data streaming from the network you can use a large value here Once you write out the whole file you can shrink it to the correct size by calling ftruncate again 5 ret ftruncate ctx fd filelen mm mmap NULL header gt filelen PROT READ PROT WRITE MAP SHARED ctx gt fd 0 if NULL mm errx 1 mmap problem memcpy mm off buf len off len Please don t forget to free mmap 2 ed memory munmap mm filelen close fd Pipelined network processing Pipelining operation Figure 2 Pipelining 72 november 2007 www linuxjournal com bas Ein mmap 2 file read gt E SE EA EA E EA ES EA BA EA SA EA BA BS Ba ES SE JA fo openttilename OSRDONEY 9 if 1 fd Cite Glan a Pile reai err NOT REACHED fstat fd amp statbf Size mm mmap NULL filelen PROT READ MAP SHARED fd 0 if NULL mm errx 1 mmap error NOT REACHED 7 Now onward you can straightaway do a memory copy of the mm pointer as it will dish out file data to you E bufptr mm off You can straightaway copy mmapped memory into the network buffer for sending memcpy pkt buf filenameoff bufptr bytes
6. RS 151 rau ne 3 Te ways if the 60 november 2007 www linuxjournal com Installation The latest version of distcc at the time of this writing is 2 18 3 There are packages for most major distributions or you can download the tarball and compile it It follows the usual automake procedure of configure make make install see the README and INSTALL files for details distcc needs to be called in place of the compiler You simply can export CC distcc for the compilers you want to replace with it but on a development workstation prefer something a little more perma nent like to create symlinks in bin and set it to be at the front of my PATH variable Then distcc always is called This approach used to work around some bugs in the version of Id that was used in building KDE and it is considered to have the widest compatibility see the distcc man page for more information mkdir bin for i in cc c gcc g do ln s which distcc bin i done If bin is not already at the beginning of your path add it to your shellrc file export PATH bin PATH setenv PATH bin PATH for bourne and C compatible shells respectively Client Configuration Each client needs to run the distcc d mon and needs to allow connections from the master host on the distcc port 3632 The daemon can be started manually at boot time by adding it to rc local or bootmisc sh depending on the distribution or eve
7. Intel Quad Core Xeon Processor E5310 1 6GHZ port Gigabit Ethernet Controller STARTING Total 1024MB 2pcs x 512MB Kingston DDR2 667MHz FB Intel ESB2 SATA 3 0Gbps Controller PRICE DIMM ECC RAID 0 1 5 10 support SERVERS DIRECT CAN HELP YOU CONFIGURE YOUR NEXT HIGH PERFORMANCE SERVER SYSTEM CALL US TODAY Our flexible on line products configurator allows you to source a custom solution or call and our product experts are standing by to help you assemble systems that require a little extra Servers Direct your direct source for scalable cost effective server solutions 1 877 727 7887 www ServersDirect com Quad core Intel Intel logo Intel Inside Intel Inside logo Intel Centrino Intel Centrino logo Celeron Intel Xeon Intel SpeedStep Itanium Pentium and Pentium Ill Xeon are trademarks of Unmatched Intel Corporation or it s subsidiaries in the United States and other countries LETTERS computer In theory the mesh network so created can mimic the Internet s TCP IP layer with a decentralized domain name system that uses distributed architecture and builds routes that connect the computers attached to its network It is as the creators say anarchical do not claim to see the future only extrapolate what seems to be an inex orable transfer of communications and data management power from the elite to the masses If you believe in people this can only be a good thing If you fear peo ple or
8. LAN onboard Red PS IO Sterage installed 20 TE BU Dual core F060 CPL 22S ist 1B Go PTT taoaapegarxrbs hiswap SATA 1I Dries installed Pert SATA II Multilana RAID 1216 Port SATA II Multiane RAID controller 2210 100 1000 onboard 1250 W Red All systems installed and tested with user s choice of Linux distribution free ASA Collocation 75 per month 2354 Calle Del Mundo WWW asacomputers com Xeon Email sales asacomputers com inside P 1 800 REAL PCS FAX 408 654 2910 Intel Intel Xeon Intel Inside amp Intel and the Intel inside lago are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and ather countries Prices and availability subject to change without notice Not responsible for typographical errors additional output from the translate node into a curves node which is set to tamp down the green channel to get rid of the green spill and help sell the different lighting conditions of the foreground vs the back ground The output of this curves node is then run into the bottom input on AlphaOver Now to complete the marriage of foreground with background we run an additional noodle from the AlphaOver node at the end of the background subtree into the top image input on the keyer AlphaOve
9. seconds Number of seconds in the past or future offset from the current second e Display the time elapsed in seconds since the UNIX epoch January 1 1970 UTC 18 november 2007 www linuxjournal com B f format Display the date and time according to formatting directives specified in format Options e and f are incompatible Specifying them together on the command line terminates the program abnormally The default output of showdate can be tweaked with the formatting directives and argument to f which are identical to the ones used by the standard date command The important thing is that all computations are performed by taking either a positive future or negative past offset from the current date and time now which is its datum A good way to become familiar with any tool quickly is to under stand how it is used For example the command to display the date and time ten years ago relative to now would be output of showdate has been omitted as the results depend on the value of now 4 showdate y 10 To find out the epoch seconds elapsed for the above scenario use showdate y 10 e A futuristic date of five years two months and 23 days from now in the YY MM DD format would be output as shown below The plus sign is optional for future dates and the two forms of the command line below are equivalent the minus sign is mandatory for past dates showdate y 5 m 2 d 23 f Y m d sho
10. ESB2 SATA 3 0Gbps Controller RAID 0 1 5 10 support Easily Scalable storage solution with hot swap functionality for growing businesses 3U Rackmount chassis with Redundant 800W power supply Seagate SATAII 500GB 7200 RPM 16MB Cache SATA 3 0Gb s Supermicro X7DBE Server Board with Intel 5000P Blackford Hard Chipset Drive Intel Quad Core Xeon Processor E5310 1 6GHZ 16x 1 Hot swap SATA Drive Bays Total 1024MB 2pcs x 512MB Kingston DDR2 533MHz FB DIMM Dual port Gigabit Ethernet Controller ECC Intel ESB2 SATA 3 0Gbps Controller RAID 0 1 10 support 4U Quad Core Xeon Server offers excellent value and expandability 4U Rackmountable Tower with 650W power supply Seagate SATAII 750GB 7200 RPM 16MB Cache SATA 3 0Gb s Supermicro Super X7DBE Server Board with Intel 5000P Hard Drive Blackford Chipset 6 x 3 5 Hot swap SAS SATA Drive Bays Intel Quad Core Xeon Processor E5310 1 6GHZ Dual port Gigabit Ethernet Controller Total 1024MB 2pcs x 512MB Kingston DDR2 667MHz FB DIMM Intel ESB2 SATA 3 0Gbps Controller RAID 0 1 5 10 support ECC Quad Core dual Xeon CPU based with 24 hot swap hard disk bays suitable for 18TB of pure data Storage capacity 50 Rackmountghassis with Redundant 1350W power supply Seagate 750GB 7200 RPM 16MB Cache SATA 3 0Gb s Hard Drive Supermicro X7DBE Server Board with Intel 5000P Blackford 24 x t Hot swap Drive Bays Chipset ntel amp ESB2 Gilgal 82563EB Dual
11. HEARTBEAT BLENDER DISTCC SCTP RAPIDMIND APIs High Performance Network Programming A SCTP Multiple Associations Since 1994 The x Community THE PRESENT AND FUTURE KING QF HPC Pane HIGH PERFORMANCE COMPUTING A RHEL Cluster Suite Heartbeat and High Availability X High Availability E Mail with Active oss e Distribute Compiles with distec a NOVEMBER 2007 ISSUE 163 HPC Cluster Solutions Enterprise and High Performance Computing Under Your Control Industry leading 4P x86 computing to boost performance and power efficiency with For information please visit ro or call Appro Sales at 800 927 5464 j AMD Opteron Processors Manage Any Data Center Anytime Anywhere Avocent builds hardware and software Co access manage and control IT asset in your data center online or offline keeping it and your business always on Visit us on our Remote Control Tour For locations near you go to www avocent com remotecontrol QFE IIA AT ARARIM AF TIIFQE QLIALAIQI SE vf H ESE OWS VEE Uo AL ANT UF INC C Infrastructure Mgt World Scottsdale AZ Booth TBD Sept 10 12 VM World San Francisco CA Booth 1113 Sept 11 13 AFCOM Data Center World Dallas TX Booth 436 Sept 17
12. Xeon inside KING STAR COMPUTER E dnd nve Intel Intel Xeon Intel Inside Intel Itanium and the Intel logo are trademarks or registered trademarks of Intel Corporation of its subsidiaries in the United States and other countries Prices and availability subject to change without notice Not responsible for typographical errors INDEPTH Multiple Associations with Stream Control Transmission Protocol The elegant way SCTP handles multiple streams makes it ideal for things like chat clients JAN NEWMARCH In two previous articles in the September and October 2007 issues of LJ looked at the basics of SCTP how you can use SCTP as a replacement for TCP and how you can use SCTP to process multiple streams within a single association In this final article look at how a single endpoint deals with multiple associations connections to other endpoints First though explain how SCTP can give extra information about what is going on through events Events The SCTP stack can generate events when interesting things hap pen By default all event generation is turned off except for data events In the last article discussed the SCTP call sctp_rcvmsg default this just returns the data read But also wanted to find out on which stream the data came and for this had to turn on the data io event so the SCTP stack would fill in the sctp sndrcvinfo structure whi
13. plex work Node based compositors available for Linux include Shake now defunct Eyeon Fusion D2 Nuke formerly of Digital Domain now owned by the Foundry and Blender Figure 2 Blender itself has long had a rudimentary track based compositing system which has received a lot of attention since Elephants Dream and has become quite useful both as a video editor and a compositor Alas because its primary purpose 15 video editing ee PS Bender atiis blend IS us aer mmn Figure 3 Finding the Nodes Editor it lacks the ability to nest compositions or layer effects as complexly as can After Effects and Motion leaving it firmly in the quick and dirty category for compositing work However with version 2 43 Blender introduced its node based compositor the jewel in the crown of the Elephants Dream improvements Professional level open source compositing has arrived and it s integrated with an otherwise very powerful 3 D content creation suite To demonstrate what it can do let s walk through a fairly simple five layer composite To get to the compositor fire up Blender and change the main 3 D window to the nodes editor Figure 3 Toggle on the Use Nodes button Because Blender uses nodes for material and texture creation as well as compositing you need to depress the picture icon By default a render scene and a com posite node will pop up In t
14. 18 High Perf on Wall Street New York NY Booth 216 Sept 17 IDC Enterprise Infra Forum New York NY Booth TBD Sept 20 Interface Salt Lake City Salt Lake City UT Booth 309 Oct 4 GEOINT San Antonio TX Booth 374 Oct 22 24 Interop New York Fall New York NY Booth 543 Oct 24 25 AFCEA Asia PAC TechNet Honolulu HI Booth 516 Nov 4 9 Super Computing Reno NV Booth 164 Nov 12 15 LISA Dallas TX Booth 200 Nov 14 15 DaCEY Awards Atlanta GA Nov 15 Gartner Data Center Conf Las Vegas NV Booth TBD Nov 27 30 Interface Seattle Seattle WA Booth 206 Nov 28 Avocent The Power of Being Therese Avocent the Avocent logo and The Power of Being There are registered trademarks of Avocent Corporation 2007 Avocent Corporation 2007 Issue 163 nIGH PERFORM COMPUTING IMAGE OISTOCKPHOTO COM NARVIKK 46 RED HAT ENTERPRISE LINUX CLUSTER SUITE 60 DISTRIBUTED COMPUTING WITH DISTCC The trusty Red Hat cluster Put your lazy machines to work Khurram Shiraz Jes Hall 52 GETTING STARTED WITH HEARTBEAT Availability in a heartbeat On Daniel Bartholomew High Performance Network Programming p 68 e SCTP Multiple Associations p 74 56 BUILDING A SCALABLE HIGH AVAILABILITY Interview with RapidMind p 64 E MAIL SYSTEM WITH ACTIVE DIRECTORY AND MORE e Heartbeat and High Availability p 52 High Availability E Mail with Ac
15. a size of 3 5 x 3 8 it can fit almost anywhere Prices start at 150 00 Please contact us for more information cae 1985 n n OVER inc sw EQUIPMENT MONITOR AND CONTROL Jh LIEN TEETH Phone 618 529 4525 618 457 0110 Web www emacinc com SOLUTIONS www linuxjournal com november 2007 19 Linux reborn in pure 64 bit form free from legacy free to fly Let the new age of Linux performance begin www pure linux X uoeyju pue g9eJng ou Soeung pue soeung Pure T J suu SOeungd 20020 Jo peJejsiDe si gxnur JO syyeuiepea For optimized peformance PureOS rec Experince pure 64 bit computing Workstation with pure performance pure speed INF H JTECH 1 800 560 6550 For maximum speed and performance we recommend Pures e SIYBU Ily 20020 soend pue go INd uoeilu pue p9eung oJn COLUMNS AT THE FORGE REUVEN M LERNER Thinking about APIs The historical evolution of Web sites into applications People are surprising and unpredictable In the computer industry you hear this in nearly every interview with the designer of a popular software package For example Perl origina
16. drops vibrations sand rain and other extremes ThinkPad tablet PCs are like other laptops with an LCD digitizer for pen based input both as a mouse and with pressure sensitivity for writing and drawing on screen www EmperorLinux com Toucan T61 T61ws Dell Latitude D830 Precision M6300 ThinkPad T61 T61ws by Lenovo e Up to 15 4 WUXGA w 1920 1200 e NVidia Quadro NVS 140M graphics e 1 8 2 4 GHz Core 2 Duo e 512 MB 4 GB RAM e 80 160 GB hard drive e CDRW DVD or DVD RW e 5 2 6 0 pounds e 10 100 1000 Mbps ethernet e 802 11a b g S4Mbps WiFi e Starts at 1650 Rhino D830 M6300 e Up to 17 WUXGA w X 1920x1200 e NVidia Quadro FX 3500M graphics e 1 8 2 4 GHz Core 2 Duo Extreme e 512 MB 4 GB RAM e 60 160 GB hard drive e DVD RW or Blu ray 6 3 8 6 pounds e 802 11a b g 54Mbps WiFi e ExpressCard EVDO e Starts at 1365 Raven X61 Tablet ThinkPad X61 Tablet by Lenovo e 12 1 SXGA w X 01400x1050 e 1 6 GHz Core 2 Duo e 1 4 RAM e 30 120 GB hard drive e 3 8 pounds e Pen stylus input to screen e Dynamic screen rotation e Handwriting recognition e 615 laptops available e Starts at 2300 1 888 651 6686 Model prices specifications and availability may vary All trademarks are the property of their respective owners TS 7800 High End Performance with Embedded Ruggedness 269 qty 1 229 qty 100 500 MHz ARM9 x New unbrickable design 3x faster
17. total So with only two extra command line options the compiler was smart enough to parallelize the loop on line 31 xautopar and honest enough to explain why two other loops lines 14 and 35 cannot be parallelized easily xloopinfo That s pretty impressive but let s see whether it got us any speedup at all export OMP NUM THREADS 4 collect prime 2000000 Creating experiment database test 2 er Number of prime numbers between 2 and 2000000 148933 er print statistics test 2 er grep Duration Duration sec 3 331 Good It isn t slower although not significantly faster either but then again we didn t have to do anything with the source code The compiler did everything for us except letting the runtime system use all the way up to four threads by setting the OMP NUM THREADS environment variable to four Or did it What about that loop on line 35 It doesn t look any more complicated than the one on line 31 Seems like the compiler is being overly conservative and we need to step in and help it a bit This time let s express parallelism with OpenMP The formal and boring definition of OpenMP states that it is an API that supports multiplatform shared memory parallel programming in C C and Fortran on all architectures including UNIX platforms and Windows NT platforms Personally I d like to think about OpenMP as a method of helping the compiler exploit data parallelism in your application when data depe
18. 800 756 5974 1 800 237 8931 www amax com WWW arrownacp com www asipartner com www bellmicro com www ingrammicro com www malabs com WWW Synnex com www techdata com 2007 Super Micro Computer Inc Specifications subject to change without notice All other brands and names are the property of their respective owners Intel the Intel logo Intel inside the Intel Inside logo Intel Xeon are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries COLUMNS BEACHHEAD JON MADDOG HALL Navigating by the Sun Lowest TCO for sale to highest bidder Dead reckoning cried Davi What is that had been adjusting the compass of my sailboat the Agape measuring for possible magnetic influences that would affect the readings and had mentioned the dead reckoning method of navigation to Davi Now knew was going to pay the price of explanation Dead reckoning is the method of determining where you are by knowing where you have been adding to that the direction and speed you have been traveling and the length of time you have been going in that direction to determine a new position It was used for many hundreds of years at sea told him Wow that must have been hard said my young friend And it must have generated many errors Yes answered and the method was blamed for the loss of hundreds of ships and thousands of lives including the
19. At the end of the day we as userland software developers have no other choice but to embrace the parallel view of the world fully Those pesky hard ware people left us no choice whatsoever For the rest of this article assume that you have at least a dual core system running Linux kernel 2 6 x and that you have Sun Studio Express installed in opt sun sunstudio and added to 80 november 2007 www linuxjournal com your PATH as follows PATH opt sun sunstudiol2 bin PATH My goal is to explain the kind of practical steps you can take to teach that old serial code of yours a few multicore tricks There are three basic steps to iterate through to add parallelism gradually to your serial application 1 Identity parallelism 2 Express parallelism 3 Measure and observe And even though the first two steps sound like the most exciting ones cannot stress enough the importance of step 3 Parallel programming is difficult and riddled with unexpected performance gotchas And there is no other way of being certain that your code got faster than proving it with numbers The good news is that it isn t all that difficult If you happen to develop mostly for Intel architectures you can use code similar to the FFMPEG s START TIMER STOP TIMER for microbenchmarking START TIMER do interesting stuff STOP TIMER do interesting stuftT tag Additionally there s the Sun Studio Performance analyzer for observing macro behaviour Yo
20. Fairchild publisher linuxjournal com Rebecca Cassity rebecca linuxjournal com Laura Whiteman laura linuxjournal com Joseph Krack joseph linuxjournal com Kathleen Boyle kathleen linuxjournal com Mark Irgang mark linuxjournal com Lana Newlander mktg linuxjournal com Mitch Frazier sysadm linuxjournal com Katherine Druckman webmaster linuxjournal com Candy Beauchamp acct linuxjournal com Linux Journal is published by and is a registered trade name of Belltown Media Inc PO Box 980985 Houston TX 77098 USA Editorial Advisory Board Daniel Frye Director IBM Linux Technology Center Jon maddog Hall President Linux International Lawrence Lessig Professor of Law Stanford University Ransom Love Director of Strategic Relationships Family and Church History Department Church of Jesus Christ of Latter day Saints Sam Ockman Bruce Perens Bdale Garbee Linux CTO HP Danese Cooper Open Source Diva Intel Corporation Advertising E MAIL ads linuxjournal com URL www linuxjournal com advertising PHONE 1 713 344 1956 ext 2 Subscriptions E MAIL subs linuxjournal com URL www linuxjournal com subscribe PHONE 1 713 589 3503 FAX 1 713 589 2677 TOLL FREE 1 888 66 LINUX MAIL PO Box 980985 Houston TX 77098 USA Please allow 4 6 weeks for processing address changes and orders PRINTED IN USA LINUX is a registered trademark of Linus Torvalds Power of 52 Processors
21. Graph bradfitz com social graph problem which presents this problem statement There are an increasing number of new social applications as well as tradi tional applications that either require the social graph or that could pro vide better value to users by utilizing information in the social graph What mean by social graph is the global mapping of everybody and how they re related as Wikipedia describes it en wikipedia org wiki Social graph Unfortunately there doesn t exist a single social graph or even multiple graphs that interoperate that s comprehensive and decentralized Rather there exists hundreds of disperse social graphs most of dubious quality and many of them walled gardens At the time Wikipedia s social network entry same as its social graph entry said Social network analysis views social relation ships in terms of nodes and ties Nodes are the individual actors within the networks and ties are the relationships between the actors Elsewhere in Wikipedia Graph is explained as a mathematical concept a set of objects called points nodes or vertices connected by links called lines or edges So the first idea is to move the center of social networking gravity outside the silo d sites each of which impose inconveniences on them selves as well as their members As Brad says People are getting sick of registering and re declaring their friends on every si
22. IS ENOUGH 1 HAVE HAD IT WITH THESE 5 KETO PENGUINS ON THIS PLANE Linux Laptops Starting at 799 Linux Desktops Starting at 375 Linux Servers Starting at 899 DONT BE SQUARE GET CUBED Technologies 309 34 i shoprcubed com JOURNAL Since 1994 The Original Magazine of the Linux Community Digital Edition Now Avatilable Read it first Get the latest issue before it hits the newsstand Keyword searchable Find a topic or name in seconds Paperless archives Download to your computer for convenient offline reading Same great magazine Read each issue in high quality PDF Samnle Tssuel www linuxjournal com digital linux o n Small Satellite MS Mas MINNS mimi eis ancl zm E TENE Ni am _ UPFRONT Frisky N800 Hack Keijo L hetkangas has a fun job at Nokia taking the company s N800 handheld com puter subject of our September 2007 cover story and turning it into the brains faces and controllers of Robot pets His Puppy and a four wheeled Rover companion were stars in the demo room at this year s Guadec confer ence in Birmingham UK Puppy is remark ably flexible and expressive It walks sits smiles dances sleeps and even how can we put this politely lifts one leg meaning that Puppy is a male or at least acts
23. Linux kernel such as tickless low power state and others 17 EX a ese imm www ibm com linux einen By the time you flip to this page SugarCRM will have its sweet new version 5 0 _ ready for you This is the ninth major release of the popular commercial open source gt customer relationship management package New features such as the ability to el build custom modules a new Ajax e mail client and a Multi Instance On Demand T architecture are said to enhance the ability to build customize scale and upgrade a the application SugarCRM says its innovations are derived from feedback from 52 2 000 commercial customers and thousands of Open Source community members af Wwww sugarcrm com Trusted Computer Solutions Security Blanket Trusted Computer Solutions has long made security solutions for the CIA and other spy agencies in Washington DC and now its new product Security Blanket aims to harden your Linux system with the same fervor Trusted Computer Solutions calls Security Blanket a system lock down and security management tool that enables systems administrators to configure and enhance the security level of the Red Hat Enterprise Linux operating platform automatically The product s advantage is to simplify the current arduous methods such as using Bastille for hardening systems Its menu driven UI allows one to r
24. Master node about the mailbox changes creating deleting and renaming mailboxes or IMAP folders in order to keep the master updated with the most current mailbox location information The Master node replicates these changes to the front end proxy nodes which direct the incoming IMAP POP3 LMTP traffic The MUPDATE protocol is used to transmit mailbox location changes Although it is not a fully redundant solution the Master node is still a single point of failure and half our users will suffer a usage outage if either one of the back end nodes is down the aggregator setup divides the IMAP processing load across multiple servers with each taking 5096 of the load As a result of this division of labor the new mail store system is now scalable to multiple servers and is capable of handling a growing user population and increasing disk usage More back end Cyrus nodes can join with the aggregator to scale up the system Integration with Active Directory One of the requirements of our new e mail system is to integrate user identities with the university directory service Because Microsoft Active Directory services have been made a standard within our centralized campus IT environment Cyrus IMAP POP3 and Postfix SMTP are architected to obtain user authentication authorization from AD After the integration all e mail user credentials can be managed from AD Most directory services are constructed based on LDAP AD uses LDAP for authorizat
25. Please don t forget to free mmap 2 ed memory munmap mm filelen close fd You can make excellent use of available bandwidth by doing things in parallel by not waiting for processing to complete before reading the next packet off the network Figure 2 illustrates what mean Pipelining is a powerful technique employed in CPUs to speed up the FETCH DECODE EXECUTE cycle Here we use the same technique for network processing Obviously your wire protocol should have the least overhead and should work without relying much on future input By keeping the state machine fairly self contained and isolated you can process efficiently Avoiding redundant protocol headers or fields that are mostly empty or unused can save you precious bandwidth for carrying real data payloads Header fields should be aligned at 32 bit boundaries and so should the C structures that represent them If your application already is in production and you want to enhance its performance try some of the above techniques It shouldn t be too much trouble to attack the problem of re engineering an application if you take it one step at a time And remember never trust any theory not even this article Test everything for yourself If your testing does not report improved performance don t do it Also make sure your test cases take of LAN WAN and if necessary satellite and wireless environments TCP has been a field of intense research for decade
26. ain t so Java s famous garbage collection got in the way of parallel programming at first Java versions as late as 1 4 use a single threaded garbage collector that stalls your Java program when it runs no matter how many CPUs you may have But Java s multithreaded design more easily exploits parallel processing than many other languages and it ended up lending itself to improvements in garbage collection JDK 5 0 includes various tuning parameters that may minimize the impact of garbage collection on multiple cores or CPUs It s not perfect and you have to take into account the way your applica tion is designed but it is a vast improvement and the improvement is made possible by the fact that Java was well conceived from the start Obviously these features aren t enough IBM builds a lot of additional parallelism into its WebSphere application server In addition IBM and other researchers are working on a Java related language X10 which is designed specifically to exploit parallel processing see x10 sourceforge net x10home shtml It is also interesting to note that when Intel boasts about its quad core performance on Java its numbers are based on using the 96 november 2007 www linuxjournal com Is Hardware Catching Up to Java BEA jRockit JVM not the Sun JVM See www intel com performance server xeon java htm for the chart and more information suspect Intel used this JVM because the BEA JVM employs garbage collec
27. an ephemeral one it can use the single socket to connect to many other endpoints and use this single socket to send messages to any of them It even can do away with an explicit connect operation and just start sending to new endpoints an implicit connection is done if no existing association exists Peeled Off Sockets One to one sockets follow the TCP model one to many sockets follow the UDP model Is it possible to have both at once Yes it is to some extent For example you may have a server that you can talk to in two modes ordinary user and superuser Messages from ordinary users may be handled in UDP style reading and just responding while superuser connections may need to be treated differently SCTP allows a connection on a one to many socket to be peeled off and become a one to one socket This one to one socket may then be treated in TCP style while all other associations remain on the one to many socket www linuxjournal com november 2007 75 INDEPTH Listing 1 chat client c include lt stdio h gt include lt stdlib h gt include lt string h gt include lt sys select h gt include lt sys types h gt include lt sys socket h gt include lt netinet in h gt include lt netinet sctp h gt define SIZE 1024 char buf SIZE define STDIN 0 char mse hello n define ECHO PORT 2013 int main int argc char argv int sockfd int nread nsent int flags len struct sock
28. and manage Widely available commodity components lead to complexity in the selection integration and testing required when building a stable system This complexity becomes doubly problematic when you consider that organizations invest in HPC systems in order to get the best possible performance for the applications they run Small variations in system architecture can have a disproportionately large impact on time to production system throughput and the price performance ratio Furthermore like any new technology the first high performance Linux clusters hit bumps in the road Early systems took a very long time for vendors to build and deliver and an even longer time to put into production Additionally early management software made re provisioning systems and upgrading components cumbersome Finally delivering HPC systems is as much about understanding the nuances of computer aided engineering CAE applications as it is 86 november 2007 www linuxjournal com about understanding technical minutiae related to interconnects processors and operating systems Early vendors of high performance Linux clusters did not necessarily have the expertise in computational fluid dynamics CFD finite element analysis FEA and visualization codes of proprietary systems vendors It is therefore natural for many to question whether the tremen dous price advantage of Linux and open systems still outweighs all other considerations The truth is tha
29. and scalability The original release of Red Hat Enterprise Linux AS version 2 1 included a high availability clustering feature as part of the base prod uct This feature was not included in the smaller Red Hat Enterprise Linux ES product However with the success of the Red Hat Enterprise Linux family it became clear that high availability clustering was a feature that should be made available for both AS and ES server prod ucts Consequently with the release of Red Hat Enterprise Linux version 3 in October 2003 the high availability clustering feature was packaged into an optional layered product called the Red Hat Cluster Suite and it was certified for use on both the Enterprise Linux AS and Enterprise Linux ES products The RHEL cluster suite is a separately licensed product and can be purchased from Red Hat on top of Red Hat s base ES Linux license Red Hat Cluster Suite Overview The Red Hat Cluster Suite has two major features One is the Cluster Manager that provides high availability and the other feature is called IP load balancing originally called Piranha The Cluster Manager and IP load balancing are complementary high availability technologies that can be used separately or in combination depending on application requirements Both of these technologies are integrated in Red Hat s Cluster Suite In this article focus on the Cluster Manager Table 1 shows the major components of the RHEL Cluster Manager Table 1 RHE
30. avoid fragmentation at any cost several HTTP servers use conservative packet sizes Doing so is not a very good thing as there is a corresponding increase in protocol overhead More packets mean more headers and wasted bandwidth Instead of using write 2 or send 2 for transfer you could use the sendfile 2 system call This provides sub stantial savings in avoiding redundant copies as bits are passed between the file descriptor and socket descriptor directly Be aware that this approach is not portable across UNIX Advanced Techniques in Application Design Applications should be well designed to take full advan tage of network resources First and foremost using multiple short lived TCP connections between the same two endpoints for sequential processing is wrong It will work but it will hurt performance and cause several Listing 3 nonblockuio c writeiovall int fd struct iov iov int nvec int i bytes i while i lt nvec do r lt writev fd amp vec i nvec i while rv 1 848 errno EINTR errno EAGAIN if rv 1 if errno EINTR amp amp errno EAGAIN perror write return ils bytes rv recalculate vec to deal with partial writes while rv gt 0 ii Y lt vecli ioy ens vec i iov char base 1 rv rv 0 else len TI 5 We s
31. begrudge them control over their own lives then you will fight it and lose Tim Copeland Practical Linux Box eagerly awaited the current issue of L September 2007 to read the Ultimate Linux Box article plan to build a system very soon and hoped to get some ideas Unfortunately just skimmed the article and was very disappointed What really would like to see is a Practical Linux Box No your sidebar Penultimate doesn t address my needs any more than the ULB Your ULB is really the Ultimate Windows Gaming Box isn t it For example look at the Display Card section It s the latest and greatest DirectX 10 card How is this a good Linux box The things I m looking for may not be what everyone else is looking for but I d like to think there are enough people to warrant some practical thinking in this type of article such as B Quiet fanless power supply and case B Small case with enough room for DVD and two hard drives B Affordable 2 000 4 000 is not prac tical or affordable B Onboard video is ok You could argue that want a media PC but that s not really my goal I d settle for one I m estimating that can build a sys tem that fits the above specs for about 700 without monitor Other names for what want might be the Quiet Linux Box or the Affordable Linux Box JT Moree The Ultimate Linux Box had nothing to do with Windows games or serving up DirectX 10 which isn t even very use
32. client SCTP applications use the TCP model by using the one to one sockets that have discussed in the previous two articles And it uses a one to many model which is more like UDP by using a one to many socket When you create a socket you specify whether it is one to one or one to many In the first article in this series created a one to one socket by the call sockfd socket AF INET SOCK STREAM IPPROTO SCTP To create a one to many socket simply change the second parameter socket AF IMET SOCK SEOPACKET IPPROTO SCTP A TCP server handles multiple connections simultaneously by essentially using concurrent reads This is done by using multiple pro cesses threads or by poll select among many sockets A UDP server typically uses a single read loop handling each message as it arrives An SCTP one to many server looks like a UDP server it will bind a socket and listen Then instead of blocking on accept which would return a new one to one socket it blocks on sctp rcvmsg which returns a message from either a new or existing association Pseudo code for such a server is sockfd socket bind sockTd s ser while true nread sctp rcvmsg sockfd buf amp info assoc id sinfo sinfo assoc id stream sinfo sinfo stream handle message assoc id stream buf nread A client also can use the one to many socket model After binding to a port probably
33. in a limited disk I O throughput 40 at maximal in an e mail system doing intensive operations To resolve the existing e mail perfor mance issues we conducted brainstorm ing sessions requirements analysis prod uct comparison and test lab prototyping We then came up with the design of our new e mail system it is named MUMAIL Figure 2 and uses standard open source software Postfix Cyrus IMAP and MySQL installed on Red Hat Enterprise Linux The core system consists of front end e mail hub and back end e mail store The front end e mail hub uses two Dell blade servers running Postfix on Linux Network load balancing is configured to distribute load between them The back end e mail store consists of two additional blade servers running a Cyrus IMAP aggregation setup Each back end node is then attached to a different storage group on the EMC Storage Area Network SAN A fifth blade server is designated as a master node to store centralized user e mail settings Furthermore we use LDAP and Kerberos to integrate the e mail user iden tities with Windows Active Directory AD Figure 3 illustrates our new e mail system architecture and the subsystem interactions with existing services which include Webmail AD and SMTP gateway The block diagrams highlighted in red are the components to be studied in detail HTTPS Related Solutions Before we zoom further into our new e mail system want to mention
34. is the perfect selection 30 november 2007 www linuxjournal com for those of you who experience a kind of mania when it comes to racecar driving The game aptly named ManiaDrive is an incredibly fast paced game with rapid turns nerve wracking jumps Figure 6 and a driving rocking soundtrack ManiaDrive is actually a clone of Nad o Studio s Trackmania game ManiaDrive features a training mode designed to prepare you for the real thing and a set of complex tracks that can be played locally or on line with other players You can get ManiaDrive from maniadrive raydium org When you start ManiaDrive make sure you go through the Beginner story which will guide you through the various moves that are expected of you When you are ready for the big time choose the Pro story mode This game is more an endurance and skill test than a race Sure there s a clock ticking and your speed is tracked on line against others no less but races last only a short time some less than a minute If you are the type that gets bored quickly ManiaDrive is for you Speaking of fast is it possible that the time has gone by so quickly Mon Dieu And yet it does appear that closing time is almost upon us Well mes amis despite the apparent crisis that we apparently faced tonight dare say the beer selection was most refresh ing can tell from your approving nods that you agree with me Nevertheless tomorrow shall have the wine cellar lock c
35. je Ge ma a my pee ee a Jmj Pii he Tip HIT pii Tin LA ur aea Peet qued Pam NEW PRODUCTS Lantronix s SecureLinx Branch Office Manager Move over Swiss Army knife Lantronix has released its new SecureLinx Branch SLB Office Manager product an IT management appliance that integrates a console server power management and an Ethernet switch into a 1U rack mountable device With SLB system administrators can securely manage a diverse range of servers and IT infrastructure equipment in branch remote offices from anywhere via the Internet SLB allows enterprises to avoid the cost of dedicated technicians and other expensive overhead at each satellite location www lantronix com Sendio s Box E Mail Integrity Service Appliance We ve been tracking the buzz surrounding Sendio s C E Box an e mail security appliance that reputedly blocks 10096 of spam with no false positives Although the I C E Box has been shipping for several months its Linux credentials recently came to our attention Shunning the antispam filter approach the I C E Box performs a one time verification that the sender of the message is someone with whom you indeed wish to communicate The result is an end to the junk while maintaining legitimate communications The appliance integrates seamlessly with any e mail server and LDAP environment A built in Kaspersky antivirus engi
36. my cluster nodes to partition the shared storage created two small primary partitions to hold raw devices and a third primary partition was created to hold the shared data filesystem Parted gt select dev sda Parted gt mklabel dev sda msdos Parted gt mkpart primary ext3 0 20 Parted gt mkpart primary ext3 20 40 Parted gt mkpart primary ext3 40 40000 rebooted both cluster nodes and created the etc syscontig rawdevices file with the following contents dev sdal dev sda2 dev raw rawl dev raw raw2 A restart of rawdevices services on both nodes will configure raw devices as quorum partitions home root gt services rawdevices restart then created JFS2 filesystem on the third primary partition using the mke2j fs command however its related entry should not be put in www linuxjournal com november 2007 49 FEATURE Red Hat Enterprise Linux Cluster Suite It is strongly recommended that fence devices hardware or software solutions that remotely power shut down and reboot cluster nodes are used to guarantee data integrity under all failure conditions the etc fstab file on either cluster node as this shared filesystem will be under the control of the Rgmanager of the cluster suite home root gt mke2jfs j b 4096 dev sda3 Now you can create a directory structure called shared data on both nodes and verify the accessibility of the shared filesystem from both cluster nodes by mounting th
37. not a real serial port If you have several serial ports exper iment to find out which is the correct one If you decide to use Ethernet you have several choices of how to configure things For simple two server clusters ucast uni cast or bcast broadcast work well The format of the ucast line is ucast device lt peer ip address gt Here is an example ucast ethl 192 168 1 39 If am using a crossover cable to connect two hosts together just broadcast the heartbeat out of the appropriate interface Here is an example bcast line bcast eth3 There is also a more complicated method called mcast This method uses multicast to send out heartbeat messages Check the Heartbeat documentation for full details Now that we have Heartbeat transportation all sorted out we can define auto failback You can set auto failback either to on or off If set to on and the primary node fails the secondary node will failback to its secondary standby state when the primary node returns If set to off when the primary node comes back it will be the secondary It s a toss up as to which one to use My thinking is that so long as the servers are identical if my primary node fails then the secondary node becomes the primary and when the prior primary comes back it becomes the secondary However if my secondary server is not as powerful a machine as the primary similar to how the spare tire in my car is not a real tire like the
38. on the console and messages TO the user from the socket 2 FD CLR sockfd amp readfds FD SET sockfd amp readfds SIDING Sreadtds s printf Selecting n select sockfdtl amp readfds NULL NULL Sreadids printf reading from stdin Nn nread read 0 buf SIZE ir read lt 0 break sendto sockfd buf nread 0 struct sockaddr amp serv addr 55 printf Reading from socket n len sizeor serv addr nread sctp_recvmsg sockfd buf SIZE struct sockaddr amp serv_addr amp len amp sinfo amp flags write 1 buf nread close sockfd 11 0 SCTP is a better choice it can sit in a read loop too but it also keeps a list of associations and better keeps that list up to date by sending heartbeat messages to the peers The list management is handled by SCTP TCP also could be a choice each client would start a new client socket on the server The server then would need to keep a list of the client sock ets and do a poll select between them to see if anyone is sending a mes sage Again SCTP is a better choice in the one to many mode it will keep only a single socket and there is no need for a poll select loop When it comes to sending messages back to all the connected clients SCTP makes it even easier the flag SCTP SENDALL that can can be set in the sc
39. only one node can run a cluster service and access cluster service data at a time The use www linuxjournal com november 2007 47 FEATURE Red Hat Enterprise Linux Cluster Suite of power switches in the cluster hardware configuration enables a node to power cycle another node before restarting that node s cluster services during the failover process This prevents any two systems from simultaneously accessing the same data and corrupting it It is strongly recommended that fence devices hardware or soft ware solutions that remotely power shut down and reboot cluster nodes are used to guarantee data integrity under all failure condi tions Software based watchdog timers are an alternative used to ensure correct operation of cluster service failover however in most RHEL cluster implementations hardware fence devices are used such as HP ILO APC power switches IBM BladeCenter devices and the Bull NovaScale Platform Administration Processor PAP Interface Note that for RHEL cluster solutions with shared storage an imple mentation of the fence infrastructure is a mandatory requirement Step by Step Implementation of a RHEL Cluster Implementation of RHEL clusters starts with the selection of proper hardware and connectivity In most implementations without IP load balancing shared storage is used with two or more than two servers running the RHEL operating system and RHEL cluster suite A properly designed cluster whether you
40. sangeeth soft release2 src show pushd home sangeeth soft release2 doc To list all the directories do the following TECH TIPS dirs l p d Suppose you make all the required changes in the first directory home sangeeth soft release2 src To remove that directory entry from the list of directories that you created earlier do the following popd The above command removes the topmost directory entry home sangeeth soft release2 src and performs cd to the new top directory which in my case will be the second directory home sangeeth soft release2 src show Alternatively one can pop a particular directory from the list of directories by giving the directory ID the ID is displayed beside a directory when using dirs 1 p d to the popd command popd 1 More options available for using the above commands can be found by viewing the man pages Sangeeth Keeriyadath Data Acquisition amp Control Computer Pac 3302 gt me Cirrus Logic EP93 200 Mhz Processor Floating Point Math Engine 2 USB 2 0 Host Ports 50 Flash Disk Slot 48 Digital GPIO Lines 1 10 100 Base T Ethernet port 5 channels of 12 bit A D amp 321 1 5232 amp 1 5232 422 485 Serial Port Battery Backed Real Time clock calendar Eclipse Linux Development Environment 5 om rU NM 2 6 Kernel The iPac has enough 1 0 for demanding applications amp with
41. service such as OpenLDAP for user authentication our design integrates user identities with Windows Active Directory AD 2 Rather than using an LDAP server to store user e mail routing settings we designed a relational database to store these settings 3 In the mail store setup instead of using an active passive high availability cluster setup like the HEC approach or the Cyrus replication approach developed at Cambridge we deployed the Cyrus Murder Aggregator Unlike the CMU Cyrus Aggregator server allocation which uses separate MTA server nodes we consolidate both MTA and Cyrus Proxy functions to run on our front end mail hub nodes We designed an e mail user database running MySQL on the Master node to serve as a centralized data store for information WAN zl Webmail IMAP Proxy un POP3 Proxy T Backend Mailstore Cyrus IMAP No 1 STudent Email Cyrus IMAP No 2 Fiber Channel SMTP SMTP Gateway Systems Spam Filtering Anti Virus Filtering SMTP 155 Frontend Email Hub mar Postfix Postis cnu MX No 2 Mailman ALAS LMTP MX No 1 diis SA im we 4 Microsoft Exchange Cluster Cx400 Figure 3 System Architecture including e mail accounts user e mail routing group aliases and mailing lists Web based user interfaces were developed using PHP to allow users to make changes to their
42. simple steps how to use an already configured RHEL cluster to provide high availability to a MySQL database server which is no doubt one of the most commonly used databases on RHEL assume that the MySQL related RPMs are installed on both cluster nodes and that the RHEL cluster already is configured with a service IP address of 172 16 2 188 Now you simply need to define a failover domain using the cluster configuration tool with the cluster node of your choice having a higher pri ority This failover domain will have the MySQL service which in turn will have two private resources and one shared resource the service IP address One of the private resources should be of the filesystem type in my configuration it has a mountpoint of shared mysqld and the other private resource should be of the script type pointing toward the etc init d mysql server script The contents of this script which should be available on both cluster nodes is shown in Listing 3 on the LJ FTP site at ftp linuxjournal com pub lj listings issue163 9759 tgz This script sets the data directory to shared mysald data which is available on our shared RAID array and should be available from both cluster nodes Testing for high availability of the MySQL database can be done easily with the help of any MySQL client used SQLyog which is a Windows based MySQL client connected to the MySQL database on Commsvr1 and then crashed this cluster node using the
43. sock opt n specify queue listen sockfd 5 printf Listening n ror ks 4 Len sizeor client addr nread sctp_recvmsg sockfd buf SIZE struct sockaddr amp client_addr amp len amp sinfo amp flags printf Got a read of d n write 1 buf nread send it back out to all associations bzero amp sinfo sizeof sinfo sinfo sinfo flags SCTP SENDALL sctp send sockfd buf nread i struct socker acli b amp sinfo 0 There also is ongoing work in bringing a security model into SCTP so that for example TLS can be run across SCTP There also is work being done on different language bindings to SCTP such as a Java lan guage binding SCTP will not make TCP and UDP disappear overnight but hope these articles have shown that it has features that can make writing many applications easier and more robust Of course SCTP is not the only attempt to devise new protocols For comparisons to other new procotols see Survey of Transport Protocols other than Standard TCP at www ogf org Public Comment Docs Documents May 2005 draft ggf dtrg survey 1 pdf This shows that SCTP stacks up very well against possible alternatives so you might want to consider it for your next networking project Jan Newmarch is Honorary Senior Research Fellow at Monash University He has been using Linux since kernel 0 98 He has written four books and many papers and given
44. some of the existing Linux UNIX e mail solutions in higher education environments First the HEC Montr al e mail system discussed in a Linux Journal article see Resources influ enced our design which is based on Cyrus IMAP and Postfix Second we looked into Cambridge University s solution It uses custom IMAP proxy front end servers and multiple pairs of Cyrus IMAP mail store servers replicating data to each other Furthermore Carnegie Mellon University CMU which originally developed Cyrus IMAP uses Sendmail as the front end mail exchanger and a Cyrus IMAP Murder Aggregator setup on the back end Columbia University moved its e mail system to a Cyrus IMAP based solution in 2006 and the University of Indiana moved to Cyrus back in 2005 Cyrus and Postfix also are used by Stanford University Although the designs of these related solutions are different most of them use a cluster based approach that separates mail transport delivery from the mail store Multiple front end MTA MDA Mail Transport Agent and Mail Delivery Agent servers are set up to deliver mail to the back end mail store which then saves messages either in a filesystem for example Maildir or a database Most of the solutions use Cyrus IMAP on UNIX or Linux as their mail store server LDAP LDAP Kerberos Detailed Design Some distinctive differences set our design apart from the existing solutions 1 Instead of using a separate directory
45. the right track The question is how we a A find the actual problem The trouble with parallel programming a Total Linux Support is that it makes some sections of your application nondeterministic That means now you have to deal with all sorts of problems you didn t have to deal with before such as race conditions and dead lock and resource allocation issues are the chief nemeses The amount of nondeter minism introduced is in fact something that makes POSIX threads quite fragile in most real life situations so much so that one of the key parallel computing researchers Professor Edward A Lee made a pretty scary prediction in his article The Problem with Threads conjecture that most multithreaded general purpose applications are in fact so full of concurrency bugs that as multicore architectures become commonplace these bugs will begin to S RTING AT 1GB DDR400 RAM 16068 SATA2 HDD INTEL BOARDS amp CPUS next generation E machines wil become 100 5 DEDICATED CISCO PORT widely known as the ones on which many 1300GB THROUGHPUT INCLUDED programs crash a ee l As you can see OpenMP even though it introduces significantly less nondeterminism LE NE NE E E E 0 0 01 1 01 1101 0101 02 1 10011 EEE E E M www linuxjournal com november 2007 83 INDEPTH Number of prime numbers between 2 and 2000000 148933 er p
46. the HP software typical or best case What software is most likely to see speed increases Database server software Complex queries on data ware housing Spam filtering Web browsers Something else McCool We have seen large speedups on a wide range of applica tions including database operations image and video processing financial modeling pattern matching and analysis many different kinds of scientific computation the list goes on and on The RapidMind platform supports a general purpose programming model and can be applied to any kind of computation The HP test was compute bound and it could take advantage of the high compute performance of GPUs However in memory bound applications we have also seen a significant benefit over an order of magnitude from running the application on RapidMind RapidMind not only manages parallel execution it also manages data flow and so can also directly address the memory bottleneck As a software platform company we are constantly surprised by the variety of applications that developers are RapidMind enabling Prior to the launch of our v2 0 product in May 2007 we had more than 1 000 developers from many different industries in our Beta program The problem is industry wide and we have developed a platform that has very broad applicability LJ Shouldn t this kind of adaptation to multiple cores take place in something more fundamental like the GNU C Library Is it only a matter of time be
47. the keying tree This takes an ASA COMPUTERS Want your business to be more productive The ASA Servers powered by the Intel Xeorf Processor provide the quality and dependability to keep up with your growing business Hardware Systems for the Open Source Community Since 1989 linux Fres BSD Openssl Solans MSs etc EC ur TTB Sterages TUE ual care 5030 GPU by CFL IGE 887HMGZ FRDIMMs Installed Support 1608 n 4X2500B hiswap SATA II Grives installed A porli SATTA 1 KAN ermis allar 2 10 10071000 LAN onboard Storage installed T2TB 3U Dual core 5050 CPL Tp 66 7113 FE DIMMs Installed Supperts 1606 FE DIMMI 16 port SATA II RAID 162 2300 8 httewap SATA Drives installed 2 10 100 1000 LAN anbeard 800w Fed Po in ATE Sterage e installed Mia 12TB Dual core 5050 CPU zi 1lab MOZ FELDIPNPNZ Installed U Suppert 16608 FROIMM 285019 E hizwap SATA II Drives installed 16 port 5A DA A AIL ellar 271 0 10071 000 LAN onboard AUU Aad FI ORR E GTO Storage inztalled hin 1878 SU Gusl core 5050 AS E B 8 ZZ FERDIMMs Inztalled 1878 44 Sat see pe Ae TE Dies ores 7i pori TAX 15 RAID CARH LVH RU gt
48. this through a network of local on the ground partner organizations Partners who know the sector and understand the needs of the IT work force Through this active policy of Regional Enablement we are seeking local partners and assisting them in their efforts to promote Linuxand Open Source professionalism We encourage you to contact our new regional partners listed above Together we are growing a world of Linux Professionals E Linux Professional Institute Stable Innovative Growing INDEPTH High Performance Network Programming in C Programming techniques to get the best performance from your TCP applications GIRISH VENKATACHALAM TCP IP network programming in C on Linux is good fun All the advanced features of the stack are at your disposal and you can do lot of interesting things in user space without getting into kernel programming Performance enhancement is as much an art as it is a science It is an iterative process akin to an artist gingerly stroking a painting with a fine brush looking at the work from multiple angles at different distances until satisfied with the result The analogy to this artistic touch is the rich set of tools that Linux provides in order to measure network throughput and performance Based on this programmers tweak certain parameters or sometimes even re engineer their solutions to achieve the expected results won t dwell further upon the artistic side of high
49. to the original title This first edi tion of what came to be called Strunk and White was version 2 0 of what began as Strunk s alone In the 86 page 1979 edition White explained A second edition of the book was published in 1972 have now completed a third revision Chapter IV has been refurbished with words and expressions of a recent vintage four rules of usage have been added to Chapter Fresh examples have been added to some of the rules and principles amplification has reared its head in a few places in the text where felt an assault could successfully be made on the bastions of its brevity and in general the book has received a thorough overhaul to Your World Runs Faster With c tree Database Technology A small footprint c tree database controls the traffic lights on your way to work Packages are scanned and delivered using a scalable c tree database that can run on handheld devices and mainframes Your financial transactions are secure because they are authenticated using a c tree database A high throughput c tree database validates your credit card transactions Your world runs faster and you sleep better Your digital pictures are well organized thanks to the transparent deployment with c tree of a c tree database within your photo database album software technology FairCom provides high performance low maint
50. use that you can get with the GPLv2 is also important you need a balance between pure technology and the kinds of pressures you get from users through the market If you have a purely marketing or customer driven approach you end up with crap technology in the end But think that something that is purely driven by technical people will also end up as crap technology in the end and you really need a balance here Linus Torvalds www linuxworld com news 2007 080907 torvalds on linux ms softwares html page z2 It s exciting to go to work each day knowing that scads of companies are using your software then contacting you to get additional value It s not easy by any stretch but it s a lot more efficient and productive than the proprietary model Matt Asay blogs cnet com 8301 13505_1 9762210 16 html part rss amp tag feed amp subj TheOpenRoad Are you Shoc ked by the high cost of iSCSI amp Fibre Channel SAN storage AlA over Ethernet Fast Reliable Simple storage www coraid com oct excellence A Winner Sr s N epee ee 4 i Solution _ Pp vere The Linux Storage People TECH 5 Display date and time in the past or future and pop through directories easily gt gt Show Date or Time Past or Future When working on Linux UNIX platforms frequently find it useful to obtain the date and time in the past or future Whether scheduling jobs searching for files
51. user The only other site can think of in this camp is Ning Marc Andreessen s build your own social network site Moreover Facebook has taken a page from Amazon and eBay telling developers that they can go wild using the Facebook network for commercial as well as nonprofit reasons Google has had a long standing policy of allowing access to its maps for example but only for publicly accessible Web sites and reasons It remains to be seen whether Facebook s API will continue to be free of charge and open to all Something this sophisticated cannot use any one of the protocols that mentioned above Rather Facebook uses a combination of protocols and techniques to com municate with your Web application making it possible for your programs to display their output alongside other Facebook applications Moreover Facebook makes it possi ble for your application to grab certain pieces of the user s Facebook data so even though your application doesn t have access to the back end Facebook database it still can know and display something about the user s friends Your application even can send messages and notifications to the user s friends although Facebook has discovered that this can lead to spamming so it remains to be seen exactly what happens on this front Conclusion Web sites used to be nothing more than an electronic method for publishing and reading basic information encoded in HTML But Web sites evolved into appl
52. which devel Opers can use and access using various protocols l ve read reports which can t confirm but that I m willing to believe claiming the majority of requests submitted to eBay s servers are through its Web services Given that most eBay users are not technically sophisticated enough to create their own HTTP clients we may assume there are a number of software development shops that see eBay as a distribution platform much as others might see Windows or Linux as their platform 24 november 2007 www linuxjournal com Google also has exposed a number of its applications to read write APIs Rather than use one of the existing protocols Google uses a version of Atom for both requests and responses along with a data format it calls GData There are read write APIs for a number of Google s applications including the calendar Blogger and the spreadsheet program Programmers no longer are limited by the interface that Google provides to their spreadsheet data they may create their own programs that use the spreadsheet for storage and retrieval One slightly far fetched example would be the creation of a distributed database server that depended on Google s spreadsheet for locking and version control Although new APIs of this sort constantly are being rolled out the trend has seemed clear Make the data easily available and downloadable by the users in a variety of formats And make it possible for them to interact with
53. x Backward compatible w TS 72xx Low power 4W at 5V 128MB DDR RAM 512MB high speed onboard Flash 12K LUT user programmable FPGA Internal PCI Bus PC 104 connector 2 USB 2 0 480 Mbps 2 SD sockets a 110 GPIO a 2 SATA ports Gigabit ethernet 10 serial ports 5 10 bit ADC Sleep mode uses 200 microamps Boots Linux in lt 2 seconds Linux 2 6 and Debian by default Design your solution with one of our engineers a Over 20 years in business Never discontinued a product Engineers on Tech Support Open Source Vision Custom configurations and excellent pricing and turn ar Most products stocked an for next day shipping See our website for options peripherals and x86 SBCs a Technologic YSTEMS A We use our stuff visit our TS 7200 powered website at www embeddedARM com 480 837 5200 UPFRONT From ACCESS to Excess The first shoe dropped in September 2005 when ACCESS Co Ltd of Japan announced that it would acquire Palm OS developer PalmSource for 324 million The next shoe dropped in February 2006 when PalmSource detailed the ACCESS Linux Platform ALP as an environment open to running Palm OS binaries and Java applications in addition to native Linux apps Enough other shoes have dropped since then to give the clear message that ALP has legs The latest was at LinuxWorld Expo in August 2007 when the company showed screenshots of an iPhone like Ul and pro
54. xt M th JON MADDOG HALLS LINUX CLUSTERS BEACHHEAD Linux in the Top 500 Navigating by the Sun David Morton LAPTOPS yrs OPEN SOURCE COMPOSITING It has been a good year for IN BLENDER innovation in Linux laptops TU Red Power compositing in Blender with many new models technologies and brands now at your disposal In next issue s Laptop Buying Guide we ll tell you what to look for and where to buy the Linux laptop that best fulfills your needs and won t bust your budget HIGH PERFORMANCE NICHOLAS PETRELEY S Dan Sawyer VAR OPINION Is Hardware Catching Up to Java IN EVERY ISSUE 4 NEW PROD 87 ADVERTISER As always there s much more Reuven M Lerner will show you how to create your own Facebook applications and Ben Martin will explain how to protect your laptop files with FUSE and an on line storage service USPS LINUX JOURNAL ISSN 1075 3583 is published monthly by Belltown Media Inc 2211 Norfolk Ste 514 Houston TX 77098 USA Periodicals postage paid at Houston Texas and at additional mailing offices Cover price is 5 99 US Subscription rate is 25 year in the United States 32 in Canada and Mexico 62 elsewhere POSTMASTER Please send address changes to Linux Journal PO Box 980985 Houston TX 77098 Subscriptions start with the next issue 4 november 2007 www linuxjournal com your cores are belong to us i i i 1 i d i
55. 18 Percentage of the 2010 digital universe for which organizations will be responsible for security privacy reliability and compliance 85 19 Exabyte capacity of media ready to store newly created and replicated data in the 2010 digital universe 601 20 Year in which the amount of information created will surpass available storage capacity for the first time 2007 1 2 which co uk sourced by David Meyer for ZDNet UK 3 4 moneysupermarket com sourced by David Meyer for ZDNet UK 5 20 Expanding the Digital Universe by John F Gantz et al a March 2007 IDC whitepaper EmperorLinux Where Linux amp laptops converge Since 1999 EmperorLinux has provided pre installed Linux laptops to universities corporations government labs and individual Linux enthusiasts Our laptops range from full featured ultra portables to desktop replacements systems come with one year of Linux technical support by phone and e mail and full manufacturers warranties apply EmperorLinux specializes in the installation of Linux on a wide range of the finest laptops made by IBM Lenovo Dell Sony and Panasonic We customize your choice of Linux distribution to your laptop and provide support for ethernet wireless X server ACPI power management USB EVDO PCMCIA FireWire CD DVD CDRW sound and more EmperorLinux offers Linux laptops with unique features Ruggedized Panasonic laptops are designed for harsh environments
56. 950W Redundant Power From 12TB to 24TB Starting at Features amp Benefits Up to 32TB of Storage Capacity Available in three Operating Systems GUI Based Linux featuring iSCSI Windows Storage Server 2003 R2 Windows Unified Data Storage Server w ISCSI Optimized SMB and NFS Performance Internal Windows OS Drive Linux 05 on DOM e Recovery from DVD or USB RAID 6 w automatic rebuild e Multi platform File Sharing Windows Linux Unix FTP Macintosh Up to 8TB Capacity Single Dual Core Intel Xeon Processor 2GB DDR2 Memory e Available as Linux or Windows NAS 500W Redundant Power From 218 to 818 otarting at 16 DRIVE 3U 5 Up to 16TB Capacity Dual Quad Core Intel Xeon Processors 2GB DDR2 Memory e Windows Storage Server 2003 500W Redundant Power From 8TB to 16TB otarting at 32 DRIVE 60 ABERNAS Up to 32TB Capacity Dual Quad Core Intel Xeon Processors e 2GB DDR2 Memory e Windows Storage Server 2003 e 1350W Redundant Power e From 16TB to 32TB Starting at Xeon inside Aberdeen surpasses HP markedly higher scores AberNAS 128 boasts outstanding features Network Computing Aberdeen AberNAS 128 Quad core Unmatched Intel Intel Logo Intel Inside Intel Inside Logo Pentium Xeon and Xeon Inside are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the Un
57. AP implementations for many languages and it continues to be used in a variety of ways despite some Take a look inside the Linux toolbox FEDORA LINUX 1000 Commands 978 0 470 08291 1 SUSE UNTU BICENTENNIAL 978 0 470 08292 8 978 0 470 08293 5 1807 WILEY Available wherever books are sold 2007 Wiley and the Wiley logo are registered trademarks of John Wiley amp Sons Inc All other trademarks are the property of their respective owners wiley com COLUMNS AT THE FORGE compatibility issues But at the same time that XML RPC and SOAP were being touted as the foundations for a new type of interac tive machine parseable Web along came Roy Fielding who described the current state of affairs as unnecessarily complex He proposed that instead of using XML in both the request and the response we instead use Representational State Transfer REST In other words the URL should contain everything needed to describe the request without any additional XML markup or payload The response of course could be in XML or any other format The idea of published Web services procedures invoked via HTTP and URLs that transferred data in XML and other formats soon became widespread Creating and using Web services became the biggest thing with every company talking about how it would take advantage of such Web services Many standards were proposed for describing and finding Web services for
58. B 8x500G Opteron 2 999 4TB 8x500GB RAID 5 Storage 3 x Gigabit LAN 6TB 12x500G Opteron 3 999 32 999 20 842555 4 x Opteron 8212 128GB ECC DDR2 2x73GB 15K RPM SAS HD 3x Gigabit LAN 16 500 5U 8850T5U 8 x Opteron 8212 64GB RAM 2TB 4x500GB HD 3 x Gigabit LAN 36 999 5U 8850T5U 8 x Opteron 8212 128GB RAM 4TB 8x500GB HD 3 x Gigabit LAN Blade Servers 10 Dual or Quad Processors Blades 24 4U Storage Server 4024SS 4U 24 Bay 13 999 8U 10 x 2055A Blades 12 24x500G Opteron 7 500 40 x Dual Opteron 2210 4GB RAM 80G HD 24 24x1000G Opteron 12 999 24 999 8U 10 x 2500A16 Blades 10 x Dual Opteron 2212 16GB RAM 80G HD 46 999 8U 10 x 8450A Blades 40 x Quad Opteron 8212 16GB RAM 80G HD 69 999 8U 10 x 8450A Blades 10 x Quad Opteron 2214 32GB RAM 80G HD AMD Dual Core technology enables one platform to meet the needs of multi tasking and multi threaded E 20 Years of Customer Satisfaction environments provides platform longevity AM D 5 Year Warranty Industry s Longest Polywell OEM Services Your Virtual Manufacturer First Class Customer Service Prototype Development with Linux FreeBSD Support ococ small Scale to Mass Production Manufacturing Wil VIII Fulfillment Shipping and Repairs p www Polywell com us LJ 7 Polywell Computers Inc 1461 San Mateo Ave South San Francisco CA 94080 650 583 7222 Fax 650 583 1974 POLYWELL Opteron Sempron and A
59. Ethernet devices to the bondO master device 3 Create a network script for the bonding device for example etc sysconfig network scripts ifcfg bondO which would appear like the following example DEVICE bond0 USERCTL no ONBOOT yes BROADCAST 172 16 2 255 NETWORK 172 16 2 0 NETMASK 255 255 255 0 GATEWAY 172 16 2 1 IPADDR 172 16 2 182 4 Reboot the system for the changes to take effect 5 Similarly on node 2 repeat the same steps with the only differ ence being that the file etc sysconfig network scripts ifcfg bondO should contain an IPADDR entry with the value of 172 16 2 183 As a result of these configuration steps you will end up with two RHEL cluster nodes with IP addresses of 172 16 2 182 and 172 16 2 183 which have been assigned to virtual Ethernet channels the underlying two physical Ethernet adapters for each Ethernet channel Now you easily can use the network configuration GUI on the cluster nodes to set other network configuration details such as hostname and primary secondary DNS server configuration set Commsvr1 and Commsvr2 as the hostnames for the cluster nodes and also ensured that names resolution in both long names and short names would work fine from both the DNS server and the etc hosts file A RHEL cluster by default uses etc hosts for node name resolution The cluster node name needs to match the output of uname n or the value of HOSTNAME in etc sysconfig network If you have an additional
60. Ethernet interface in each cluster node it Listing 1 Contents of the etc hosts File on Each Server Do not remove the following line or various programs that require network functionality will fail 127 0 0 1 localhost localdomain localhost 172 Za LEZ Commsvr1 Commsvr1 kmefic com kw 172 16827 155 Commsvr2 172 161 1956 Commilol Commilol kmefic com kw 1 10 5T 2187 Commi 102 Commilo2 kmefic com kw L72 o lOs Za LOE Commserver 192 195 19 1 1 197 166 19 7 node2 T7216 24 KMETSM is always a good idea to configure a separate IP network as an addi tional network for heartbeats between cluster nodes It is important that the RHEL cluster uses by default ethO on the cluster nodes for heartbeats However it is still possible to use other interfaces for additional heartbeat exchanges For this type of configuration you simply can use the network configuration GUI to assign IP addresses for example 192 168 10 1 and 192 168 10 2 on eth2 and get it resolved from the etc hosts file Setup of the Fencing Device As was using HP hardware relied on the configuration of the HP ILO devices as a fencing device for my cluster However you may consider configuring other fencing devices depending on the hardware type used for your cluster configuration To configure HP ILO you have to reboot your servers and press the F8 key to enter into the ILO configuration menus Basic configuration is rela tively simple you ha
61. H SCTP NAVICORE AMD MAEMO MAPPER Phone A cress MOURN E ULTIMATE LINUX HANDHELD ULTIMATE LINUX BOX ULTIMATE LINUX LAPTOP Your Wish Is Our Command would love to see a detailed explanation on the new Completely Fair Scheduler in the Linux kernel including areas where it may be inferior to the existing scheduler and where it excels Also I d like to see an explanation of the tickless patches which apparently result in significant power savings Chris Thompson We ll look into a scheduling article but we have an article on power savings in the works includ ing information on the tickless patches Ed The Arcade Game Machine Is Hot was very interested to read Shawn Powers article on building an arcade machine based around Linux L August 2007 However one thing that concerns me is the lack of reference to cooling issues If a PC is in a wooden box for any period of time without a fan to force cool air through there would be a risk of heat dam age to the machine particularly the CPU and the hard drive www coker com au energy computer power html The above URL has the energy use of some computers have owned at various times the idle tests were idle at a Linux prompt idle at a DOS prompt or the BIOS uses significantly more power You will note that a PA machine uses significantly more power than a PIII can only guess at the relative power requirements of a PIII and the origi
62. L Cluster Manager Components SOFTWARE SUBSYSTEM COMPONENT fenced libdlm dim kernel cman GFS and related locks Lock_NoLock gulm Rgmanager clurgmgrd clustat ccsd ccs_test and ccs_tool Cluster Configuration Tool System config cluster magma and magma plugins iddev be run in standalone mode but introduces a single point of failure for GFS Three or five GULM servers also can be run together in which case the failure of one or two servers can be tolerated respectively GULM servers usually are run on dedicated machines although this is not a strict requirement In my cluster implementation used DLM and it runs in each cluster node DLM is good choice for small clusters up to two nodes because it removes quorum requirements as imposed by the GULM mechanism Based on DLM or GLM locking functionality there are two basic PURPOSE Provides fencing infrastructure for specific hardware platforms Contains distributed lock management DLM library Contains the Cluster Manager CMAN which is used for managing cluster membership messaging and notification Contains shared filesystem support that can be mounted on multiple nodes concurrently Contains the GULM lock management user space tools and libraries an alternative to using CMAN and DLM Manages cluster services and resources Contains the cluster configuration services daemon ccsd and associated files Contains the C
63. LAN with servers that use GNBD Global Network Block Device or two iSCSI Internet Small Computer System Interface devices Both GFS and CIVM use locks from the lock manager However GFS uses locks from the lock manager to synchronize access to filesystem metadata on shared storage while CLVM uses locks from the lock manager to synchronize updates to LVM volumes and volume groups also on shared storage For nonconcurrent RHEL cluster implemen tations you can rely on CIVM or you can use native RHEL journaling based techniques such as ext2 and ext3 For nonconcurrent access clusters data integrity issues are minimal tried to keep my cluster implementations simple by Shared Storage and Data Integrity Lock management is a common cluster infrastructure service that provides a mechanism for other cluster infrastructure components to synchronize their access to shared resources In a Red Hat cluster DLM Distributed Lock Manager or alternatively GULM Grand Unified Lock Manager are possible lock manager choices GULM is a server based unified cluster lock manager for GFS GNBD and CIVM It can be used in place of CMAN and DLM A single GULM server can using native RHEL OS techniques Fencing Infrastructure Fencing also is an important component of every RHEL based cluster implementation The main purpose of the fencing implementation is to ensure data integrity in a clustered environment In fact to ensure data integrity
64. MUMAIL has been running in production for ten months The entire system has been running in a stable state with minimal downtime throughout this period All user e mail messages originally on HOBBIT were moved successfully to MUMAIL in a three day migration window with automated and non disruptive migration processes Users now experience significantly faster access speed Their e mail storage quota is raised from 20MB to 200MB and there is potential to increase the quota to a higher number 1GB With the installation of gateway level spam virus firewalls as well as increased hardware speed no e mail backlog has been experienced on MUMAIL during recent spam virus outbreaks With an Active Directory integrated user authentication setup user passwords or other sensitive informa tion are no longer stored on the e mail system This reduces user confusion and account administration overhead and increases network security Mail store backup speed is improved significantly with faster disk access in the SAN environment Finally the new system has provided a hardware and software environment that supports future growth with the adoption of a scalable design More server nodes both front end and back end and storage can be added when system usage grows in the future Jack Chongjie Xue holds a Masters degree in Information Systems from Marshall University where he did Linux and Windows systems administration work His job du
65. Opteron Model 840 2GB Memory 128 GB Supports upto 64GB FBDIMM 80 GB SATA Hotswap Hard Drive 2xIntegrated Dual 10 1000 LAN b 5U Dual AMD Opteron Model 246 iSCSI or NAS Software Options Support upto 18TB of Storage Fail Hard Drive LED Indicator 1 Dual AND Opteron Tm storage Stars ot 5845 8U AMD Opteron Model 246 4TB of Storage 36TB Max 1GB RAM 2 x 10 100 1000 Gigabit LAN NAS or iSCSI Software Options E E E EI a We Provide Approved EVAL Server since 1989 ASA has served customers like Cisco Juniper Caltech Fermilab and most Universities We provide a total custom solution with OS of your choice Excellent pre and post sales support Reliable hardware at the most competitive prices Please call or contact us for your next hardware purchase 2254 Calle Del Mundo Santa Clara 95054 wwW asacomputers com Email Sales asacomputers com Tel 1 800 REAL POS Fax 408 664 2910 Ordinary processing INDEPTH Listing 4 mmap c ha ERIS Ga Pa a Ead Ge mmap 2 file write 5 SESE SAREE SB GPUs CHES RS ESE SESE SAS ES o CES EI EIAS caddr_t mm NULL fd open filename O RDWR O TRUNC O CREAT 0644 if 1 fd errx 1 File write NOT REACHED
66. THLON are trademarks of Advanced Micro Devices Inc Quadro nForce and Nvidia are trademarks of NVIDIA Corporation All other brands names are trademarks of their respective companies Opteron COLUMNS WORK THE SHELL DAVE TAYLOR Keeping Score in Yahtzee Push an array sort out to the sort function instead of writing a sort routine Last month started talking about how to use some simple shell scripting techniques to create a computer sim ulation of the popular dice game Yahtzee l m not going to write the entire game the computer player would be darn complicated for a shell script for one thing but let s spend one more column looking at some of the basics of scoring before we move on to other topics One nice thing about Yahtzee as a computer game is that there really isn t much work for the computer to do because the game works fine as a solitaire variation you simply can play to try to maximize your score and see how you do competing against your previous high score The basic idea of Yahtzee is that you roll five dice up to three times to get the best possible set of values Those are then scored against a fixed score pad that offers spe cific points for specific combinations ranging from one point per one in your roll up to 50 points for five of a kind a Yahtzee in game parlance A quick visit to Google identifies an on line Yahtzee score sheet take a look at it before we proceed www gami
67. The main advantages of this paradigm are the speed of work for simple and moderately complex effects and the ease of navigation for new users who already are familiar with Photoshop Figure 1 The second paradigm the node based paradigm is the one that appears in the high end professional compositors It works by chaining together various image functions to create complex effects Image functions are mathematical transforms applied to an image to change it in one way or another LAE IC ND Figure 2 A Node Based Interface and they reside at the base of anything one does in GIMP or ImageMagick or in video compositing These functions are encapsulat ed in the interface by nodes A node works a bit like a guitar pedal it accepts inputs and generates outputs and those outputs can be routed to an infinite number of other nodes Thus in a node based compositor one uses the node chains to accomplish one s goal and there typically are two types of nodes from which to choose One type is the famil iar user friendly prepackaged effects plugins such as one would find in the Photoshop universe The other type is a set of mathe matical interfaces that allow you to build custom effects yourself This has the disad vantage of being far more visually complex and for some people much harder to learn However for that steeper learning curve the artist gets a much more versatile work flow which is better suited to doing highly com
68. Vs a chance to certify their applications Red Hat s v5 0 had been out for only a month or so at the time of the data effectiveness cited in an e mail message on April 4 2007 This is hardly enough time for the ISVs to certify their software on top of Red Hat s newest release and and get it into Red Hat s system Again there s nothing wrong or illegal it s just a little sleazy as a marketing ploy okay more than a little sleazy Suns claim that Red Hat makes migration more difficult brings about the question migration from what Last night went to my Linux user group meeting and the speaker who was running a mixed Solaris and Linux shop lamented how hard it was to work on a Solaris system because of the antiquated and nonstandard set of utilities on the upper levels of the operat ing system His presentation confirmed some of the issues knew about and showed that being a Sun customer was not all peaches and cream But then again do not expect Sun s marketing group to haul out the spoiled milk Sun also claims binary compatibility between releases but when you actually read Sun s terms and conditions on binary compatibility it basically says Sun guarantees your program to run as long as you did not use any interfaces that did not change or were not deleted This is a guarantee It sounds like most of the warranties in the EULAs of most software products have seen basically worthless received a final e mail messag
69. WWW cari net 8 UJ Mikro www routerboard com CORAID INC www coraid com 4 Poco LINUX www pogolinux com Coyote POINT www coyotepoint com POLYWELL COMPUTERS INC www polywell com E EMAC INC www emacinc com NO THE PORTLAND GROUP WWw pgroup com NJ EMPERORLINUX www emperorlinux com UJ www qsol com FAIRCOM www faircom com W NO RACKSPACE MANAGED HOSTING www rackspace com C UJ GENSTOR SYSTEMS INC www genstor com m N R CUBED TECHNOLOGIES www rcubedtech com HPC SvsrEMs INC www hpcsystems com SERVERS DIRECT www serversdirect com HURRICANE ELECTRIC www he net SiLICON MECHANICS www siliconmechanics com N UJ INFITECH www infi tech com NJ O SUPER MICRO COMPUTER INC Wwww supermicro com UJ UJ INTEL www intel com W ssl TECHNOLOGIC SYSTEMS www embeddedx86 com A KiNG STAR COMPUTER www kingstarusa com N UJ UNIWIDE TECHNOLOGIES www uniwide com wk LINUX JOURNAL www linuxjournal com Eom WILEY TECHNOLOGY PUBLISHING www wiley com N UJ www linuxjournal com november 2007 81 INDEPTH 44 45 return 0 46 Granted the code is silly some might even say brain dead bu
70. a position of pious hypocrisy They are the biggest thieves of all Also pathetic are the many pop stars now grown rich and fat sucking on the corporate tit who parrot the RIAA s line It matters not The only reason artists and record companies ever had control over music media was that it was impractical for listeners to create their own Given that ability most listeners will follow my own common sense creed when get the data it s my data and l Il do with it what damn well please The RIAA hands down morality lessons while cracking the lawsuit whip in hope of putting the file sharing genie back in its bottle They pretend that there is some moral code that forbids consumers to copy and give away music media Their morality is based on laws that were manufactured by a Congress eager to be bribed It s easy to burst the RIAA s moral bubble Just travel back to 1850 in your mind and go hear a music performer In 19th century America the artists played and the people enjoyed It had been that way for 10 000 years If the artists were lucky or very good they could make a living by performing Many do that to this very day It is an honest liv ing They work at what they love It s their job It was a temporary quirk of technology that allowed artists and record companies to turn performances into commodities to be bought and sold A few lucky artists could perform record and then sit back and let the bucks roll in while t
71. absolutely always must be up and running for the business to keep functioning smoothly These servers provide services that always need to be available whether it be a database DHCP DNS file Web firewall or mail server A cornerstone of any service that always needs be up with no downtime is being able to transfer the service from one system to another gracefully The magic that makes this happen on Linux is a service called Heartbeat Heartbeat is the main product of the High Availability Linux Project Heartbeat is very flexible and powerful In this article touch on only basic active passive clusters with two members where the active server is providing the services and the passive server is waiting to take over if necessary Installing Heartbeat Debian Fedora Gentoo Mandriva Red Flag SUSE Ubuntu and others have prebuilt packages in their repositories Check your distribution s main and supplemental repositories for a package named heartbeat 2 After installing a prebuilt package you may see a Heartbeat failure message This is normal After the Heartbeat package is installed the package manager is trying to start up the Heartbeat service However the service does not have a valid configuration yet so the service fails to start and prints the error message You can install Heartbeat manually too To get the most recent stable version compiling from source may be necessary There are a few dependencies so to p
72. addr in serv addr sctuuct o setpsspdrevilbo SO iY aree l 2 4 fprintf stderr usage s argv 0 Xo b create endpoint using SCTP sockfd socket AF INET SOCK SEQPACKET TPRROROSSCTPOS ir sockie lt 4 perror socket creation failed 11 2 serv addr sin family AF INET serv addr sin addr s addr inet addr argv 1 serv addr sin port htons ECHO PORT if connect sockfd Lazy Person s Chat In this section discuss a simple example of how to build a simple chat server using SCTP This isn t meant to be a competitor to the many chat systems around rather it is to show some of the features of SCTP A chat server must listen for messages coming from a probably transient group of clients When a message is received from any one dient it should send the message back out to all of the other clients UDP could be a choice here a server simply can wait in a read loop waiting for messages to come in But to send them back out it needs to keep a list of clients and this is a bit more difficult Clients will come and so some sort of liveness test is needed to keep the list up to date 76 november 2007 www linuxjournal com struct sockaddr amp serv addr sizeof serv addh lt 0 perror connect to server failed EIE printf Connected Win while 1 we need to select between messages FROM the user
73. all know these standards still exist but for the average programmer they don t and I m not sure if and when they ever will Read Write APIs Given two read only protocols and three read write proto cols it was a matter of time before people started to create applications that would take advantage of these Amazon was one of the first companies to do so opening up its catalog in a set of Web services now known as Amazon E Commerce Services or ECS Amazon made its entire catalog available via ECS and it allowed program mers to choose between SOAP and REST Over the years ECS has become an increasingly sophisticated and capable system making it possible to retrieve particular slices of Amazon s catalog and pricing information But retrieving information from Amazon is only half the story Amazon also makes it possible to manage a shopping cart via ECS and even has some facilities for managing third party products for sale Amazon has made a huge commitment to ECS and a large community of developers and third party software vendors now exist around this facility By turning Amazon into a platform for software development rather than a simple on line store Amazon simultaneously has made a community of people dependent on ECS and has created opportunities for the creation of software applications that otherwise never would have been built eBay Google and Yahoo among others also have provided a number of APIs via Web services
74. ame daemon in a connected mji mi pj M d nn CTDAIAL n CAIDA MORE PRODUCTS BETTER SERVICE GUARANTEED KEEP YOUR BUSINESS RUNNING SMOOTHLY PROTECT YOUR SMALL BUSINESS WITH THE BUILT IN SECURITY ENHANCEMENTS OF THE DUAL CORE INTEL XEON PROCESSOR IN YOUR SERVERSDIRECT SYSTEM SOR 11057 1 ENTRY LEVEL SERVER EXCELLENT GENERAL PURPOSE SERVER FOR ORGANIZATIONS WITH THE NEED FOR A LOW ENTRY LEVEL PRICE 10 Rackmount Chassis with 520W power supply Supermicro X DVL L Server Board with Intel 5000V Blackford VS Chipset Intel Quad Core Xeon Processor E5310 1 6GHZ Total 512 2pcs x 256MB Kingston DDR2 533Mhz FB DIMM ECC Seagate SATAII 160GB 7200 RPM 8MB Cache SATA 3 0Gb s Hard Drive 4x 1 Hot swap SATA Drive Bays Two Intel 82563EB Dual port Gigabit Ethernet Controller Intel ESB2 SATA 3 0Gbps Controller RAID 0 1 5 10 support Highest performing with Dual Core Quad Core Xeon CPU based Excellent with general purpose applications 4 and provide the most power 3 2U Rackmount Chassis with 650W power supply Seagate SATAII 250GB 7200 RPM 16MB Cache SATA 3 0Gb s Hard Supermicro X7DVL E Server Board with Intel 5000V Blackford VS Drive Chipset 6 x 1 Hot swap SATA Drive Bays STARTING Intel Quad Core Xeon Processor E5310 1 6GHZ Intel ESB2 Gilgal 82563EB Dual port Gigabit Ethernet Controller PRICE Total 512MB 2pcs x 256MB Kingston DDR2 533Mhz FB DIMM ECC Intel
75. an be used by setting a kernel build configuration flag 9 Linux FreeBSD x86 solaris MS etc IE Proven technology Proven reliability When you can t afford to take chances with your business data or productivity rely on GS 1245 Server powered by the Intel Xeon Processors Ideal for high density clustering in standard 1U form factor Upto 16 Cores for high CPU needs Easy to configure failover nodes Features 1U rack optimized chassis 1 75in Up to 2 Quad Core Intel Aeon Woodcrest per Node with 1333 MHz system bus Up to 16 Woodcrest Cores Per 1U rackspace Up to 32GB DDR2 667 amp 533 SDRAM Fully Buffered DIMM FB DIMM Per Node Dual port Gigabit Ethernet Per Node 2 SATA Removable HDD Per Node 1 x8 PCI Express Per Node Servers Storage Appliances Genstor Systems Inc 780 montage 604 Email sales genstor com Phone 1 877 25 SERVER or 1 408 383 0120 INDEPTH Listing 2 chat server c include lt stdio h gt include lt stdlib h gt include lt strings h gt include lt sys types h gt include lt sys socket h gt include lt netinet in h gt include lt netinet sctp h gt define SIZE 1024 char buf SIZE define CHAT PORT 2013 int main int argc char argv int Ssocktd Client ine nsent Len struct sockaddr in serv addr client addr Str ct sctpe sngarcvilTo 5 Tho ine tlaes
76. and empirical data as well as proven techniques As mentioned previously it is an art best perfected by practice and it s also an iterative process However once you get a feel for how things work it will be smooth sailing The moment you build a stable base for a fast client server interaction like this building powerful P2P frameworks on top is no great hassle Girish Venkatachalam is an open source hacker deeply interested in UNIX In his free time he likes to cook vegetarian dishes and actually eat them He can be contacted at girish1729 gmail com Resources Polipo User Manual www pps jussieu fr jch software polipo manual TCP Tuning and Network Troubleshooting www onlamp com pub a onlamp 2005 11 17 tcp_tuning html Wikipedia s Definition of Bandwidth en wikipedia org wiki Bandwidth Advanced Networking Techniques beej us guide bgnet output html multipage advanced html TCP and Congestion Control Slides www nishida org soi1 mgp00001 html Unbeatable Price Quality amp Service 1U Supermicro 6015B TV Customized System 2x Xeon Quad Core E5335 2GHz CPU 4GB 667mhz FB DIMM 2x 250GB HD Slim DVD 2U Supermicro 6025B TR B Like above spec 2x Xeon E5335 CPU 4GB RAM 2x 250GB w Redundant Power 8 hotswap bays Free gadget w purchase M amp aue e nons Windows redhat fedora solaris Customizable system solutions since 1989 Tel 1 800 875 8590 Fax 408 736 4151 intel
77. are building a RHEL based cluster or an IBM HACMP based cluster should not contain any single point of failure Keeping this in mind you have to remove any single point of failure from your cluster design For this purpose you can place your servers physically in two separate racks with redundant power supplies You also have to remove any single point of failure from the network infrastructure used for the cluster Ideally you should have at least two network adapters on each cluster node and two network switches should be used for building the network infrastructure for the cluster implementation Software Installation Building a RHEL cluster starts with the installation of RHEL on two cluster nodes My setup has two HP Proliant servers DL740 with shared fiber storage HP MSA1000 storage started with a RHEL v4 installation on both nodes It s best to install the latest available oper ating system version and its updates selected v4 update 4 which was the latest version of RHEL when was building that cluster If you have a valid software subscription from Red Hat you can log in to the Red Hat network and go to software channels to download the latest update available Later once you download the ISO images you can burn it to CDs using any appropriate software During the RHEL OS installation you will go through various configuration selections the most important of which are the date and time zone configuration the root us
78. ars of experience under their belts vendors and architects of high performance Linux clusters are better equipped than ever to design stable tuned systems that deliver the desired price performance and enable customers to get the most out of their application licenses First generation systems may have been difficult to manage but the newest generation comes equipped with advanced cluster man agement software greatly simplifying operations By selecting an expe rienced vendor many of today s clusters are delivered as full featured systems as opposed to an unwieldy pile of stitched together commodity components As a result users benefit from both lower acquisition costs and easy to use high performance systems The maturity of the Linux HPC industry also contributes to a deeper understanding of the codes users rely on as well as the hardware that goes into building a system Certain vendors have become experts at tuning systems and optimizing Linux to meet and overcome the challenges posed by widely used HPC applications For example most high performance structures codes such as those from ANSYS or ABAQUS require high I O to sustain higher rendering rates Conversely crash impact codes don t require much I O to run optimally they are designed to run in parallel in systems where the average CPU count is 16 Linux has evolved to the point where it is now very easy for vendors to build systems that accommodate the needs of these code
79. at filesystem one by one at each cluster node mount dev sda3 shared data However never try to mount this filesystem on both cluster nodes simultaneously as it might corrupt the filesystem itself Cluster Configuration Almost everything required for cluster infrastructure has been done so the next step is configuring the cluster itself A RHEL cluster can be configured in many ways However the easiest way to configure a RHEL cluster is to use the RHEL GUI and go to System Management Cluster Management Create a cluster created a cluster with the cluster name of Commcluster and with node names of Commsvr1 and Commsvr2 added fencing to both nodes fencing devices Commilo1 and Commilo2 respectively so that each node would have one fence level with one fence device If you have multiple fence devices in your environment you can add another fence level with more fence devices to each node also added a shared IP address of 172 16 2 188 which will be used as the service IP address for this cluster This is the IP address that also should be used as the service IP address for applications or databases like for listener configuration if you are going to use an Oracle database in the cluster added a failover domain namely Kmeficfailover with priorities given in the following sequence Commsvr1 Commsvr2 added a service called CommSvc and then put that service in the above defined failover domain The next step i
80. at when issuing the make command you need to specify multiple jobs so that the other machines in the cluster have some work to do As a general guide the number of jobs should be approx imately twice the number of CPUs available So for a setup with three single core machines you would use make j6 For three dual core machines you would use make j 12 If you have removed localhost from your list of hosts don t include its CPU or CPUs in this reckoning Preprocess Compile Compil 0 Local hast i Compil n tsxdr c Prap wvlan c 197 168 659 178 0 192 168 63 128 1 S 9_055_ Aidi file c INE TE igwal k i ntsdzdr e nls Compile Compil 5 statsz c Preprocess Compile file Preprocess alloc c Compil nfsaxdr c Figure 1 distccmon text Monitoring a Compile distcc includes two monitoring tools that can be used to watch the progress of compile jobs The console based distccmon text is particularly excellent if your master host is being accessed via SSH As the user the compile job is running as execute the command distccmon text s where s is the number of seconds at which you would like it to refresh For example the following distccmon text 5 updates your monitor every five seconds with compile job information The graphical distccmon gnome is distributed as part of distcc if you compile from source but it may be a s
81. ation For network configuration the best way to proceed is to use the network configuration GUI However if you plan to use Ethernet channel bonding the configuration steps are slightly different Ethernet channel bonding allows for a fault tolerant network connection by combining two Ethernet devices into one virtual device The resulting channel bonded interface ensures that if one Ethernet device fails the other device will become active Ideally connections from these Ethernet devices should go to separate Ethernet switches or hubs so that the single point of failure is eliminated even on the Ethernet switch and hub level To configure two network devices for channel bonding perform the following on node 1 1 Create bonding devices in etc modules conf For example used the following commands on each cluster node alias bondO bonding options bonding miimon 100 1 Doing this loads the bonding device with the bondO interface name and passes options to the bonding driver to configure it as an active backup master device for the enslaved network interfaces 2 Edit the etc sysconfig network scripts ifcfg ethO configuration file for ethO and the etc sysconfig network scripts ifcfg eth1 file for the eth 1 interface so that these files show identical contents as shown below DEVICE ethx USERCTL no ONBOOT yes MASTER bondO SLAVE yes BOOTPROTO none This enslaves ethX replace X with the assigned number of the
82. ation environments www motorola com 42 november 2007 www linuxjournal com Olive s OPUS 3075 Who knows where you ll find Linux next One sure spot is the embedded brain inside Olive Media Products new OPUS 3075 audio system The OPUS 3075 part of Olive s OPUS N 3 product line is a stylish audio component that goes in your stereo rack and contains all of your digital music on its 250GB hard drive The OPUS can store up to 700 CDs in lossless quality Improvements on the OPUS 3075 over previous Olive devices include perpendicular recording technology for lower power consumption higher storage density improved long term reliability and inaudible operation In addition Olive will preload up to 300 of your CDs for free www olive us Black Duck Software s protexIP Software development with open source code is great but it can be complicated This is why Black Duck Software created protexlP development now v4 4 a platform that helps compa nies govern how their software assets are created managed and licensed protexIP helps developers and legal counsel in managing the use of code from open source projects who have explicitly decided to switch to GPLv3 and those that have not Also included is an enhanced KnowledgeBase a library of open source and vendor added code software components with detailed licensing information for more than 140 000 components www blackducksoftware com wv fe pa m fenem
83. cannot afford the solution you cannot implement it the really interesting indicator is Return on Investment ROI and long term benefits which I call Value of Investment VOI VOI is usually what a company wants for the long run Regarding the claim that Red Hat 5 0 does not save you money Sun offered one example of a solution offered to Marc Andreessen 5 5 solution was cheaper than Linux on Intel commodity hardware Okay fine But this particular customer also was Marc Andreessen and having worked in the UNIX Group at Digital Equipment Corporation DEC for 16 years can imagine the discussion between the various management groups inside Sun to make sure it won this account and to make sure it was a good deal of which there is no detailed analysis of the terms listed in the e mail or on the site There is nothing wrong illegal or even immoral about this deal and its subsequent use in marketing and certainly not on Marc s part it s just a bit opportunistic by Sun to use a well known name on a single deal to make its point not scientific by any means As for the claim that Solaris supports more certified applications than Red Hat v5 0 Sun used the application base of its SPARC and its x86 architectures combined How many people want to run both a SPARC and an Intel box just to get the complete suite of applications Additionally the Solaris OS version had been out for a while giving independent software vendors IS
84. ch has the sinfo stream field Events are listed in the sctp event subscribe structure struct ctp event subscribe 4 uintS t sctp data 1o event uint8 t sctp association event uint8 t sctp address event uintB t sctp send failure event uint8_t sctp peer error event uint8 t sctp shutdown event uint8 t sctp partial delivery event uint8 t sctp adaptation layer event uint8_t sSctp authentication event An application sets fields to one for events it is interested in and zero for the others It then makes a call to setsockopt with SCTP EVENTS For example memset amp event 0 sizeof event event sctp data io event 1 event sctp association event 1 sersockopt TO SCTP SCTP EVENTS amp event sizeof event Events are delivered inline along with ordinary data whenever a read using sctp recvmsg or similar is done If the application turns on events reads will contain a mixture of events and data The applica 74 november 2007 www linuxjournal com tion then will need to examine each read to see whether it is an event or data to be processed This is quite straightforward If the flags field in the sctp_recvmsg call has the MSG NOTIFICATION bit set the read message contains an event otherwise it contains data as before Pseudo code for this is nread sctp rcvmsg msg if flags amp MSG NOTIFICATION handle event msg oxy amp f lags else handle_data msg
85. courses on many technical topics concentrating on network programming for the last six years His Weh site is jan newmarch name 21ST LARGE INSTALLATION SYSTEM ADMINISTRATION CONFERENCE BERR _ a 4 rs 8 A LISA 07 offers the most in depth practical system administration training available 6 DAYS OF TRAINING BY EXPERTS IN 3 DAY TECHNICAL PROGRAM INCLUDING THEIR FIELDS INCLUDING Keynote by John Strassner Motorola Fellow and Vice President Tom Limoncelli on Time Manage Autonomic Networking and Communications Motorola Research Labs ment for System Administrators on Autonomic Administration HAL 9000 Meets Gene Roddenberry e Steve VanDevender on High Invited Talks by industry leaders discuss important and timely topics Capacity Email System Design including e Frisch on Administering Bruce Moxon NetApp Service Oriented Data Grid Beyond Linux in Production Environments Storage Virtualization Faisal N Jawdat on Introduction to e Erik Nygren Akamai Technologies Experiences with Scalable Ruby Rails and Capistrano Network Operations at Akamai e Kenneth C Brill Uptime Institute The Economic Meltdown of Moore s Law ji Refereed Papers Hit the Ground Running Track Guru Is In Sessions Ven
86. created by enclosing a sequence of operations on RapidMind types between RM BEGIN and RM END The operations will then be stored in the Program object For example suppose we want to add a value f represented using a global variable to every element of an array We would create a program object prog as follows Program prog RM BEGIN InsValuelf c Out Valuelf d cT RM END Note that although the program may run on a co processor we can just refer to external values like f in the same way we would from a function definition It is not necessary to write any other code to set up the communication between the host processor and any co processors To apply this operation to array a and put the result in array b invok ing a parallel computation we just use the program object like a function b prog a Of course in real applications program objects can contain a large number of operations and a sequence of program objects and collective operations on arrays such as scatter gather and reduce would be used LJ How do you avoid the common pitfalls of parallel process RapidMind s Founder and Chief Scientist Michael McCool left and President and CEO Ray DePaul right ing such as deadlocks or other synchronization issues McCool The semantics of the RapidMind interface does not involve explicit locking or synchronization by the developer The platform itself automatically takes care of these issue
87. d to solve DePaul RapidMind is a multicore software platform that allows software organizations to leverage the performance of multicore processors and accelerators to gain a real competitive advantage in their industry With RapidMind you can develop parallel applica tions with minimal impact on your development lifecycle costs and timelines And we allow you to accomplish this without the need for multithreading You leverage existing skills existing compilers and IDEs and take advantage of all key multicore architectures without constantly porting your application LJ So is it accurate to say RapidMind is actually a library of common operations where the exploitation of multiple cores is largely transparent to the programmer McCool RapidMind is much more than a simple library of canned functions In fact it is possible to use the API to the RapidMind platform to specify an arbitrary computation and for that computation to execute in parallel with a very high level of performance We provide a sophisticated multicore software platform that can leverage many levels of parallelization but at the same time allows developers to express their own computa tions in a very familiar single threaded way 64 november 2007 www linuxjournal com NICHOLAS PETRELEY LJ How much if anything does the programmer need to know about parallel processing programming techniques in order to use RapidMind McCool We believe that
88. developers are the application experts and should have some involvement in moving their applications into the parallel world The key is to let developers leverage what they already know rather than force them down an unfamiliar and frustrating path RapidMind is built upon concepts already familiar to all developers arrays and functions It is not necessary for a developer to work directly with threads vectorization cores or synchronization Fundamentally a developer can apply func tions to arrays and this automatically invokes parallel execution A RapidMind enabled program is a single threaded sequence of parallel operations and is much easier to understand code and test than the multithreaded model of parallel programming LJ Can you give us a simple code example the includes and declaration statements that would start a typical program McCool First you include the platform header file and optionally activate the RapidMind namespace include rapidmind platform hpp using namespace rapidmind Next you can declare variables using RapidMind types for numbers and arrays Valuelf f Array lt 2 Value3f gt a b The Value1f type is basically equivalent to a float and the Array types are used to manage large collections of data These can be declared anywhere you would normally declare variables as members of classes or as local or global variables A Program object is the RapidMind representation of a function and is
89. ding both of which run at 29 97 frames per second fps Because it s a European program and has historically been an ani mation program the closest approximation it can hit is 30fps Though 3fps seems like a trivial difference it s more than enough to slip your sound sync beyond the limits of intelligibility so it s far better to work with image sequences and then re multiplex your audio with your video in your video editing software such as KDENLIVE or OpenMovieEditor The keying subtree begins with a curves node which pushes the green in the greenscreen into a narrow band to make it easier for the keyer to latch on to Then the output links to the input of a channel keyer set to pull the cleanest possible matte which accomplished by hooking a viewer node to the image output so could see what was doing when played with the settings The resulting matte is then run through a blur node Normally when keying DV footage would apply a 4x2 blur to soften the matte and compensate for the edge artifacting introduced by the DV compression However in this case my edges were dark because of how lit the original scene and needed some extra feathering so the brightness from the background would bleed over The output of this blur node is then piped into the Fac input of an AlphaOver node which marries the greenscreen footage to the rest of the image But I m getting ahead of myself Let s back up to the other half of
90. dor Exhibition Workshops BoFs WiPs and more zi e p Pajp 3 MEL LOL LS LJ Li Uu L WNILNEEWILTUCCTENFENEURNER EN uL on 0 wem emm amen eim rm fe poem LT LE Ce DLE L Sponsored by LISENIX Register by October 19 and save www usenix org lisa07 lj INDEPTH Roman s Law and Fast Processing with Multiple CPU Cores Some practical methods to exploit multiple cores and find thread synchronization problems ROMAN SHAPOSHNIK Computers are slow as molasses on a cold day and they ve been like that for years The hardware industry is doing its work but computers are not going to get any faster unless the software industry follows suit and does something about it Processing speed is less about GHz and more about multiple cores these days and software needs to adapt will be so bold as to postulate my own law of the multicore trend for hardware the number of cores on a chip would double every three years It remains to be seen whether going to be as accurate in this prediction as Gordon Moore happened to be but it looks good so far With Intel and AMD introducing quad core systems and Sun pushing the envelope even further with its first hexadeca core CPU named Rock th
91. e Building a highly available solution using the RHEL cluster suite When mission critical applications fail so does your business This often is a true statement in today s environments where most organi zations spend millions of dollars making their services available 24 7 365 days a year Organizations regardless of whether they are serving external customers or internal customers are deploying highly avail able solutions to make their applications highly available In view of this growing demand almost every IT vendor currently is providing high availability solutions for its specific platform Famous commercial high availability solutions include IBM s HACMP Veritas Cluster Server and HP s Serviceguard If you re looking for a commercial high availability solution on Red Hat Enterprise Linux the best choice probably is the Red Hat Cluster Suite In early 2002 Red Hat introduced the first member of its Red Hat Enterprise Linux family of products Red Hat Enterprise Linux AS origi nally called Red Hat Linux Advanced Server Since then the family of products has grown steadily and it now includes Red Hat Enterprise 46 november 2007 www linuxjournal com KHURRAM SHIRAZ Linux ES for entry and mid range servers and Red Hat Enterprise Linux WS for desktops workstations These products are designed specifically for use in enterprise environments to deliver superior appli cation support performance availability
92. e applies to writing code One difference is that writers of prose generally need to be instructed on the value of brevity while writ ers of code do not That may seem a harsh or inaccurate statement but make it because code is purposeful in ways prose does not have to be In fact blather is some times the very purpose of prose Garrison Keillor once called English the preacher s language because it allows you to talk until you think of what to say suppose you can blather in code too Back in the late 1990s was sitting in the office of Phil Hughes Linux Journal s founder and publisher He had just come from an argumentative session with a group of geeks in another room Imagining would know what he was talking about he threw a pile of code printout onto his desk Look at that he said Six pages of Perl could have done the same thing in one page of awk I m not saying Perl is blather by the way though Phil might am saying that omit ting needless words is a code writing value for which prose writers require help from the likes of William Strunk Version 1 5 of Strunk and White came with a 1935 revision by Edward A Kenny titled The Elements and Practice of Composition Strunk died in 1946 Far as know his book didn t change until 1957 when the writer E B White once a stu dent of Strunk s came again upon the little book and set about improving it with two short additional chapters and a return
93. e editing features but also because of the large number of plugins that were developed and sold for the platform Microsoft Office much as it might be reviled by many Linux and open source advocates became popular because of its built in programming language as much as for its built in features And of course the Firefox browser wouldn t be half as useful to me if it weren t for the half dozen plugins that have added to my software So users push software to the limits and software publishers have been able to make their offerings more useful by making it possible to extend their programs How does this translate into an era of Web based software And what does this mean to us as Web developers The answer is the increasingly ubiquitous application programming interface or If you want your Web site to be taken seriously as a platform and not just an appli cation you need to offer an API that lets users create modify and extend your application APIs are becoming an 22 november 2007 www linuxjournal com increasingly standard part of Web based applications but despite everyone s use of the term API that acronym means different things to different people Starting next month I m going to look at the latest batch of APIs that sites such as Facebook are offering But this month want to take a step back and consider the different types of APIs that software publishers offer This is useful if you intend t
94. e on June 28 2007 inviting me to tell Sun why used Linux and offering me a free 4GB iPod Nano if came in for a one hour meeting to listen to why should use Solaris would get the iPod if signed up and if was qualified and if the number of iPods 25 had not been depleted Hmm not that even want an iPod but what was the chance of getting that iPod That s not illegal or immoral or even sleazy just marketing Why am making a big deal about what obviously is a badly positioned marketing campaign After all was in the marketing group for DEC the last eight years of my employment there know what it s like in a large company with many product groups and many marketing strategies that often run in conflict with each other imagine some people inside Sun really believe in FOSS and the community and gnash their teeth whenever they hear of such things even know one First Sun purports to be a friend of the Free and Open Source community and a reseller of Linux and Linux hardware It has had four of its server systems certified by at least one Linux distribution and it is listed as a Gold Partner of that Linux distribution assume that it is making money doing this and perhaps even is selling services for those servers and the Linux systems on them But then hear reports and receive e mail messages that show this is simply a bait and switch program to get Linux customers onto its cus tomer list and convince them to
95. e question the software industry has to ask itself is Are we ready to make all these execu tion threads do useful work for us My strong opinion is that we are not ready A new paradigm is yet to be invented and we don t really know what it should look like What we do know however in the words of Herb Sutter is The biggest sea change in software development since the OO revolution is knocking at the door and its name is Concurrency The first layer of software where hardware parallelism is going to percolate is the kernel of your operating system And know of only two kernels that have what it takes to tackle the chal lenge Solaris and Linux If there s any Mac OS X or dare say Windows fanboys out there have two phrases for you 256 processor systems and Completely Fair Scheduler Now having a kernel that is capable of efficiently multiplexing a large number of processes to a large number of hardware threads is only as good as your demand in actually having that large number of indi vidual processes running in parallel And as much as it is an ISP or provisioning person s dream come true on my laptop rarely have more than four really active processes running at the same time The real need that have is for each individual application to be able to take advantage of the underlying hardware parallelism And that s how a fundamental hardware concept permeates yet another software layer an application one
96. e same goes for Ruby Python Perl C and The code samples in the SCTP why does that make me think of John Candy article are excellent in this regard steeve 10 november 2007 www linuxjournal com JOURNAL At Your Service MAGAZINE PRINT SUBSCRIPTIONS Renewing your subscription changing your address paying your invoice viewing your account details or other subscription inquiries can instantly be done on line www linuxjournal com subs Alternatively within the U S and Canada you may call us toll free 1 888 66 LINUX 54689 or internationally 1 713 589 2677 E mail us at subs linuxjournal com or reach us via postal mail Linux Journal PO Box 980985 Houston TX 77098 0985 USA Please remember to include your complete name and address when contacting us DIGITAL SUBSCRIPTIONS Digital subscriptions of Linux Journal are now available and delivered as PDFs anywhere in the world for one low cost Visit www linuxjournal com digital more information or use the contact information above for any digital magazine customer service inquiries LETTERS TO THE EDITOR We welcome your letters and encourage you to submit them to ljeditor linuxjournal com or mail them to Linux Journal 1752 NW Market Street 200 Seattle WA 98107 USA Letters may be edited for space and clarity WRITING FOR US We always are looking for contributed articles tutorials and real world stories for the magazine An author s guide a
97. e wheel and drive Repeat what you just told me Francois No Don t tell me that Yes Francois know told you to repeat what you told me but was sincerely hoping was mistaken and that had heard something entirely dif ferent Something like Patron lost the key to the filing cabinet not I lost the key to the wine cellar In my first restaurant job Francois this would have been considered a firing offense No mon ami am not going to fire you but this is terrible What shall we serve our guests Non see them walking toward the restaurant now Quickly Francois think of something Why you Because you locked up the wine cellar minutes before opening time then proceeded to lose the key That s why Quoi Serve beer from my personal r frig rateur de bi re That is not a bad idea at all mon ami You live to serve another day non Don t look so hurt Francois We have guests Quickly Ah welcome everyone to Chez Marcel where fine Linux fare is served with the most excellent wines from one of the world s premier wine cellars that is except tonight It seems my faithful waiter has lost the keys to the wine cellar Never fear mes amis though I love that won drous liquid fruit of the grape your Chef also enjoys a good beer be it lager or ale So tonight s menu will be accompanied by selections from my own r frig rateur de bi re Please sit and make yourselves comfortable Francois can offer you sev
98. eats out of the box and notice that America has become this country in a sample text to forestall a subsequent and possibly demeaning she in the same paragraph Astute readers of Strunk White and Linux Journal will observe that we violate one of the former pair s original commands by putting our punctuation outside our closing quotation marks unless it is part of the quotation This complies with a Linux Journal copy editing policy established by Phil Hughes in 1994 in compliance with what had already become geek vernacular One of my first arguments with Phil was over this very practice lost Today if you look for The Elements of Style at Amazon com you ll find three different books The 1999 fourth edition Strunk s original edition and The Elements of Style Illustrated which Wikipedia tells us is the fourth edition plus illustrations by Maira Kalman Somehow can t help regarding the three as distributions of Strunk s patched kernel each useful in its own way It s also interesting to read and compare the discussion and history pages behind the Wikipedia entry for The Elements of Style The former calls to mind the Linux Kernel Mailing List LKML while the latter serves as a kind of code repository These analogies are far from precise but there is a common purpose in usefulness What brought me to this fresh appreciation of usefulness was a blog post by Alan Mitchell titled Beyond the persuasion paradig
99. ed RSS standing either for really simple syndication or RDF site summary In either case the idea was to create a machine readable frequently updated summary of a site s contents By checking a site s RSS feed you could learn whether there had been any updates More significant RSS feeds were formatted in a standard way with standard tags making it fairly easy for programs to poll a feed and extract only the information they wanted Unfortunately the term RSS became both the generic term for syndication and the name for several incompati ble but similar formats for syndication A separate group of developers created the Atom protocol which many people believe is superior to all of the various RSS formats 1 RSS and Atom are still popular today The most common use of these syndication feeds is for blog and news updates allowing users to keep track of which sites have updated their content But RSS and Atom can be used in other ways as well providing a simple reliable and machine readable version of various types of data from a Web site If you are looking to broadcast regularly updated data RSS and Atom probably are going to be a good starting point For example the well known development company 37signals provides an Atom feed of recent activity in its Highrise contact management system As helpful as it might be to look at your own feed it would be even more helpful to aggregate multiple people s feeds into a single v
100. ed on open source software The incorporation of Postfix Cyrus IMAP and MySQL helped to fulfill most of the system requirements From the hardware per spective the technologies used such as Storage Area Network SAN blade server and the Intel x86 64 CPUs helped meet the requirements of fast access system scalability and high availability However the use of open source software and new hardware technologies may introduce new management overhead Although all the open source software packages used on the new system are mature products compared with commercial software they typically lack a GUI for system management Their configuration and customization are completely based on a set of plain text configuration files Initially this may present a learning curve as the syntax of these configuration files must be studied But once the learning curve is passed future management easily can be automated as scripts can be written to manage the configuration parameters and store them in a centralized location On the hardware side complex settings also may imply complex network and server management settings which also may introduce overhead during system management However the benefits of using the technologies discussed outweigh the complexities and learning curves involved It is easy to overcome the drawbacks through proper design configuration management and system automation At the time of this writing our new Linux e mail system
101. el almost did Intel has been working on what it calls the Thread Building Blocks TBB C library and its claim to fame is exactly that making modern parallel Give it a try and see If it works for you especially recommend it if you re interested in exploiting task parallelism But then again the amount of modern C that TBB throws at even the simplest of examples such as calculating Fibonacci numbers is something that really makes me sad Tasks as defined in the upcoming OpenMP 3 0 standard seem far less threatening Conclusion There is a fundamental trend toward concurrency in hardware Multicore systems are now making their way into laptops and desk tops Unfortunately unless software engineers start taking these trends into account there 5 very little that modern hardware can do to make individual applications run faster Of course parallel pro gramming is difficult and error prone but with the latest tools and programming techniques there s much more to it than merely POSIX threads Granted this article scratches only the surface of what s available Hopefully the information presented here will be enough of a tipping point for most readers to start seriously thinking about concurrency in their applications Our high definition camcorders demand it and so does every gamer on earth Roman Shaposhnik started his career in compilers back in 1994 when he had to write a translator for the programming language he d ju
102. enance data management technology Our customers ranging from small startups to multinational corporations are able to overcome application specific performance dilemmas because c tree gives them precise control over their database operations Super charge your application and simplify your deployment Download an evaluation edition of c tree today Download FairCom s c tree Plus Today Fair Com ww faircom com go usesDLD High Performance Database Technology 800 234 8180 Other company and product names are registered trademarks or trademarks of their respective owners 2007 FairCom Corporation COLUMNS LINUX FOR SUITS correct errors delete bewhiskered entries and enliven the argument White died in 1985 The 1999 fourth edition of the book has a forward by White s stepson Roger Angell plus an index a brief afterward by Charles Osgood and a glossary by Robert DiYanni The current entry in Wikipedia notes An anonymous editor modified the text of this 1999 edition Among other changes he or she removed White s spirited defense of he for nouns embracing both genders See the they entry in Chapter IV and also gender specific pronouns In his forward Angell puts it more gently This edition has been modestly updated with a light redistribution of genders to permit a feminine pronoun or female farmer to take their places among the males who once inno cently served him Sylvia Plath has knocked K
103. ence improves performance for net work I O But if you use mmap 2 with NFS you are asking for trou ble Listing 4 shows a code snippet that illustrates the use of mmap 2 for both reading and writing files Socket Options and sendfile 2 TCP sockets under Linux come with a rich set of options with which you can manipulate the functioning of the OS TCP IP stack A few options are important for performance such as the TCP send and receive buffer sizes sndsize 16384 setsockopt socket SOL SOCKET SO SNDBUF char amp sndsize int sizeof sndsize rcvsize 16384 setsockopt socket SOL SOCKET SO RCVBUF char amp rcvsize int sizeof rcvsize am using conservative values here Obviously it should be much higher for Gigabit networks These values are determined by the bandwidth delay product Interestingly have never found this to be an issue so doubt if this would give you a performance boost It still is worth mentioning because the TCP window size alone can give you optimal throughput Other options can be set using the proc pseudo filesystem under Linux including the above two and unless your Linux distribution turns off certain options you won t have to tweak them It is also a good idea to enable PMTU Path Maximum Transmission Unit discovery to avoid IP fragmentation IP fragmentation can affect not just performance but surely it s more important regarding performance than anything else To
104. endors and which architectures should they support By leverag ing RapidMind they get to benefit from all of the hardware innovations and deliver better products to their customers within their current development cycles and timelines RapidMind will continue to provide portable performance across a range of both processors and operating systems We will support future multicore and many core processors so applications written with RapidMind today are future proofed and can automatically take advantage of new architectures that will likely arise such as increases in the number of cores LJ Can you tell us more about your recently demonstrated support for Intel and AMD multicore CPUs DePaul It s difficult to overstate the value we bring to software companies targeting Intel and AMD multicore CPUs For example at SIGGRAPH in San Diego we demonstrated a 10x performance improvement on an application running on eight CPU cores RapidMind enabled applications will scale to any number of cores even across multiple processors and will be tuned for both Intel and AMD architectures Software organizations can now target multicore CPUs as well as accelerators such as ATI and NVIDIA GPUs and the Cell processor all with the same source code LJ Is there anything else you d like to tell our readers DePaul It s becoming clear that software organizations plans for multicore processors and accelerators will be one of the most important initiat
105. eparate package depending on your distribution It provides similar information in a graphical dis play that allows you to see at a glance which hosts are being heavily utilised and whether jobs are being distributed properly It often takes www linuxjournal com november 2007 61 FEATURE Distributed Compiling with distcc It doesn t require a large cluster of compile hosts to be useful significant compile time decreases can be seen by merely adding one other similarly powered machine a few tries to get the order of hosts at the most optimal tools like distccmon gnome make it easier to see whether machines are being under or over utilised and require moving in the build order Host slot Alle State Taska Preprocess IIA Mili Mil Preprocess 1 1 11 reprocess Preprecess BUT IM Eii NEII HIN INI IH 1927 16A 63 178 bitmap 192 168 63 128 cifeencrypt c 192 168 63 128 resize c 192 168 63 129 sound core c xattr trusted c 192 168 63 129 localhost dir c Compile services c Compile 1 2 02 192 168 63 125 1 2 0 localhost 1 Fi localhost Load average 8 60 5 52 2 60 Figure 2 Graphical distcc Monitoring Security distcc relies on the network being trusted Anyone who is able to con nect to the machine on the distcc port can run arbitrary commands on that host as the distcc user It is vitall
106. er 2 amp 4 Sockets up to 128GB memory 3U Server 2 amp 4 Sockets up to 128GB memory Workstation 1 2 amp 4 Sockets up to 128GB memory www bellmicro com Ce www avnet com SYNNEX WWW Synnex com Applied Computing Solutions 1 888 300 8277 PORATION 1 888 756 4888 www uniwide com UNIWIDE elo gt 1 877 520 0071 Uniwide is an official AMD Validated Server Program Partner Copyright 2007 Uniwide Technologies Inc All right reserved Specifications are subject to change without notice iff Linus Torvalds di u has expressed keen interest in finding 5 NEW someone to put IN KERNEL together a full git DEVELOPMENT repository of the kernel going all the way back to version 0 01 He s tried this himself a couple times and other folks have made various efforts but it s a hard problem Certainly it would not be possible to include every patch that went into the kernel in the order it was included because many patches never were sent to any public forum Even finding the release announcements for all the numbered versions will be difficult and some official releases are thought to be lost as well It s a daunting task but a very valuable one even if done incompletely If someone can do it Linus has offered to comment the various early patches and releases from memory Mingming Cao has submitted patches to allow the ext4 filesystem to perform checksum calculations
107. er password setting firewall settings and OS security level selection Another important configuration option is network settings Configuration of these settings can be left for a later stage especially in building a high availability solution with Ether channel or Ethernet bonding configuration You may need to install additional drivers after you install the OS In my case downloaded the RHEL support package for the 01740 servers the HP Proliant support pack which is available from h18004 www1 hp com products servers linux dl740 drivers cert html The next step is installing the cluster software package itself This package again is available from the RHEL network and you definitely have to select the latest available cluster package selected rhel cluster 2 4 0 1 for my setup which was the latest cluster suite available at the time 48 november 2007 www linuxjournal com Once downloaded the package will be in tar format Extract it and then install at least the following RPMs so that the RHEL cluster with DLM can be installed and configured 7 Magma and magma plugins Perl net telnet M Rgmanager System config cluster 9 and dlm kernel 9 DLM kernel hugemem and SMP support DLM Iddev and ipvsadm 7 Cman cman smp cman hugemem and cman kernelheaders M Ccs Restart both RHEL cluster nodes after installing vendor related hardware support drivers and the RHEL cluster suite Network Configur
108. eral excellent selections all favorites of mine including Alexander Keiths India Pale Ale Kilkenny Irish Cream Ale Sleeman s Original Unibroue Maudite and several others As you know mes amis this issue s theme is high performance which we all know can refer only to rac ing and automobiles If the words high performance and Linux don t immediately generate the same associ ation in your mind you should know that in point of fact Linux and car racing go very well together The 2007 Indianapolis 500 featured the first ever Linux sponsored car The brainchild of Ken Starks aka helios the Tux500 Project succeeded in its aim to raise enough money to place Tux the familiar Linux mascot created by Larry Ewing on the hood of an Indy car For more details go to www tux500 com 1 26 november 2007 www linuxjournal com Figure 1 The Tux500 Indianapolis racecar notice the logo on the hood In honor of this momentous event the first race game on tonight s menu SuperTuxKart features the very same Tux at the wheel SuperTuxKart maintained by Joerg Henrichs is an updated and enhanced version of the original TuxKart created by Steve Baker If you ve played the original you ll be impressed by the new hugely improved SuperTuxKart The game features slick new graphics new tracks cool characters racing adven tures and more You take the controls as one of several characters including Tux Penny his friend Mr Ice Bloc
109. ercomputing in both vendor and end user roles to Linux Networx Dave is responsible for leading the Linux Networx technology vision and directing the hardware software and system engineering teams Previously Dave served as technical director for the Maui High Performance Computer Center where he was responsihle for the definition and oversight of technology for this Department of Defense supercomputing center He held several positions at SGI including director of server 1 0 and continuation engineering and director of Origin platform engineering Dave s experience includes eight years at Cray Research where he was named inventor on three issued patents Dave earned a Master s degree in Mechanical Engineering from the University of Illinois and an MBA from the University of Minnesota www linuxjournal com november 2007 87 _ INDEPTH Blender How to use node based compositing in Blender DAN SAWYER Linux is bursting with multimedia poten tial at least that s the impression one gets from the plethora of multimedia oriented dis tributions that have surfaced in recent years DeMubDi Planet CCRMA Ubuntu Studio 64 Studio and the list continues on ad infini tum However for many years now the term multimedia proved deceptive GIMP and Inkscape and other graphics tools meant that 2 D graphics were covered and the astound ing variety of audio tools available with real time priority meant that users needs for recordi
110. ere the links guided me Although the message does identify several features that Solaris has built in some of those features are offered by major Linux distributions and others can be added by rolling your own in the Linux space Two of the major features Sun offers are low cost licensing and support options and a disruption free migration path from the difficulties of a Linux platform to the ease and value of a Solaris 10 solution Hmm sounds a bit like marketing hype to me 34 november 2007 www linuxjournal com Then on June 27 2007 I received another letter from Sun A lot of myths have been circulating about Linux that it s low cost that it runs more apps that it s pervasive but when you look at the facts you see a different story Red Hat 5 0 does not save you money runs fewer cer tified applications and makes migration more difficult These are just three of the many compelling facts that should make you wonder why are you running Linux when you could be running Solaris 10 OS Now Total Cost of Ownership TCO studies abound showing how Microsoft is cheaper than Sun Sun is cheaper than Linux Linux is cheaper than Microsoft and so on Normally these TCO studies show whatever the sponsoring company wants them to show and it does not take heaps of intelligence to realize that a TCO study that does not show the desired winner would not see the light of day Although TCO is important because if you
111. ery simple routine for calculating how many prime numbers there are between 2 and N 1 include lt stdio h gt 2 include lt stdlib h gt 3 include lt math h gt 4 include lt omp h gt 5 6 pflag v 1 if and only if v is a prime number 7 char pflag 8 9 int is prime int v 10 d 11 int 3 12 int bound floor sqrt v 1 13 14 i 9 2 1 lt bound i 4 15 if 1 0 16 pflagiv 9 17 return 0 v is NOT a prime number 18 19 20 return 1 v is a prime number 2l j 22 23 int main int argc char argv 24 25 int 35 26 int total 0 27 int N atoi argv 1 28 int primes N array of prime numbers 29 pflag char alloca N 30 31 ror Cr 25 y NY 445 4d 32 pflag i 1 all numbers are prime until 33 proven otherwise T 34 35 for i 2 i lt N i let the testing begin 36 if is primeli 4 37 primes total i 38 1 39 40 41 42 printf Number of prime numbers between 2 and d d n 43 N total Advertiser Advertiser ABERDEEN LLC www aberdeeninc com LISA 07 www usenix org events usenix07 APPRO HPC SOLUTIONS appro com NJ LOGIC SUPPLY INC www logicsupply com ASA COMPUTERS www asacomputers com LPI www lpi org AVOCENT CORPORATION www avocent com remotecontrol MICROWAY INC www microway com CARI NET
112. es though for now going to go play with my freshly compiled desktop environment m Jes Hall is a UNIX systems consultant and KDE developer from New Zealand She s passionate about helping open source software bring life changing information and tools to those who would otherwise not have them HeariYourselft rhinkeAgain WhisperStation Cool Fast Silent For 64 bit HPC Gaming and Graphic Design Applications Originally designed for a group of power hungry demanding engineers in the automotive industry WhisperStation incorporates two dual AMD Opteron or Intel EM64T processors ultra quiet fans and power supplies plus internal sound proofing that produce a powerful but silent computational platform The WhisperStation comes standard with 2 GB high speed memory an NVIDIA e GeForce or Quadro PCI Express graphics adapter and 20 LCD display It can be configured to your exact hardware specification with any Linux distribution RAID is also available WhisperStation will also make a system administrator very happy when used as a master node for a Microway cluster Visit www microway com for more technical information Technology you can count INDEP TH Picking the RapidMind RapidMind has a mind to make advances in the use of multicore programming rapidly available Writing applications to support multiple CPU cores is not an easy task and in so
113. ete PO Box 980985 Filing Date September 10 2007 Addresses of Publisher Editor Houston TX 77098 Issue Frequency Monthly and Managing Editor Joyce Searls Number of Issues Published Publisher Carlie Fairchild PO Box 980985 Annually 12 PO Box 980985 Houston TX 77098 Annual Subscription Price 25 Houston TX 77098 Adele Soffa Complete Mailing Address of Editor Doc Searls PO Box 980985 Figure 11 The Completed Project Known Office PO Box 980985 Houston TX 77098 of Publication Houston TX 77098 Known Bondholders mE P PO Box 980985 Managing Editor Mortagees and Other Security image processing functions is included that the capabilities are Houston TX 77098 Jill Franklin Holders Owning or Holding 1 d d t db f Blender rt for Contact Person Mark Irgang PO Box 980985 Percent or More of Total very deep and extensive anc because blenders Support 713 589 3503 Houston TX 77098 Amount of Bonds Mortages HDR formats such as OpenEXR and its lack of limitation on reso Complete Mailing Address of or Other Securities None T iti it Ibeit Headquarters of General Tax Status Has not Changed utions it is squarely in the professional compositing camp albei Business Office of Publisher During Preceding 12 Months at the less sophisticated end of the 5 ue would Publication Title Linux Journal 14 Issue Date October expect fr
114. etwork in many if not most cases especially high performance computing environments You can use some other form of persistent storage but today none matches the huge storage capacity that hard disks offer Currently most applications on the Internet push several gigabytes of data and you end up with heavy storage needs anyway To test disk performance type this hdparm rT dev sda dev hda if IDE Check whether you are getting good throughput If not enable DMA and other safe options using this command hdparm d 1 A 1 m 16 u 1 a 64 dev sda Listing 2 uio c include lt sys types h gt include lt sys uio h gt include lt unistd h gt Size t wri ini fd Struct Int CME size t pos 0 55 eS lov ent while gt pos poll wait fd POLLOUT POLLERR res Whitey id Tov Ol 10y base pos N switch int res case 1 if errno EINTR errno EAGAIN return errno ERIRE return pos pos size return pos 70 november 2007 www linuxjournal com We also need to be able to avoid redundant copies and other time consuming CPU operations to squeeze the maximum bandwidth from the network A very effective tool for achieving that is the versa tile mmap 2 system call This is a very useful technique for avoiding the copy to buffer cache and h
115. event SUDSchIbe Events assoc id create endpoint sockfd socket AF INET SOCK SEQPACKET PRRROTORS GIDE lt 0 4 NULL 2 pind address serv_addr sin_family AF_INET serv addr sin addr s addr htonl INADDR ANY serv addr sin port htons CHAT PORT if bind sockfd struct sockaddr amp serv addr addr lt 0 4 m MPI Message Passing Interface www mpi forum org is a de facto standard for communication among the processes modeling a parallel program on a distributed memory system according to Wikipedia It does not specify which transport protocol should be used although TCP has been common in the past Humaira Kamal in his Master s thesis investigated using SCTP as a transport protocol and reported favourable results He singled out the causes as being the message based nature of SCTP and the use of streams within an association These examples show that SCTP is being used in a variety of real world situations to gain benefits over the TCP and UDP transports Conclusion This series of articles has covered the basics of SCTP There are many options that can control in fine detail the behaviour of an SCTP stack 78 november 2007 www linuxjournal com perror NULL exit 3 bzero amp events sizeof events Events sctp data o event 1 sersockopt scekia DPPROTOSSCEPS SCTE SEVENIS D perror set
116. f us are still free to improve Doc Searls is Senior Editor of Linux Journal He is also a Visiting Scholar at the University of California at Santa Barbara and a Fellow with the Berkman Center for Internet and Society at Harvard University The Straight Talk People gi SINCE 1959 9 1 ABERDEEN HERE IS HOW THE BEST STACK UP 1 O00 woe gt Wa b 00 4 1 v 1 7 g 070 d 4 m 107 E 000 J I la it I LET i B 0 i i D LI 4 4 000 TOR Li L7 xv 00000000 L ww PETTI t LL za 10000000 i amp i i i X i i i k LT i LISS 1 DRIVE 10 ABERNAS 3 DRIVE 20 ABERNAS Up to 4TB Capacity e Intel Pentium 4 Processor e 1GB DDR Memory e Available as Linux or Windows NAS e 300W Power Supply e From 1TB to 4 Starting at 12 DRIVE 2U ABERNAS Up to 12TB Capacity e Single Dual Core Intel Xeon Processor e 2GB DDR2 Memory e Available as Linux or Windows NAS e 500W Redundant Power e From 9TB to 1218 Starting at 24 DRIVE 5U ABERNAS Up to 24TB Capacity Dual Quad Core Intel Xeon Processors 2GB DDR2 Memory Windows Storage Server 2003
117. for technical sales or email sales microway com S AffordablejinfiniBandiSolutions FasTree DDR InfiniBand switches Low latency modular design 24 36 and 48 port building blocks ottenere 4 lt s A TF tae A niyen O Per ri N m ees 0 i ai Teenie A ee m Om OE p InfiniScope Monitors ports on HCA s and switches Provides real time BW diagnostics Finds switch and cable faults Lane 15 interface Logs all IB errors Technology you can count on
118. for you who believe in free and open source software and what the corporate management and marketing culture states is the direction of the company Here is my beef am a Linux Guy I believe in free and open source software and this means more than just the open source licenses that Sun offers It means that customers easily can contribute back to the path that Sun as a company takes and it means that customers easily can contribute back to the code that Sun writes It means that as a business partner can feel free to propose my solutions to my customers without having my partner run roughshod over me have found my solution to free and open source software in the Linux kernel and the people and companies building and contributing to it That said when engage customers engage them with the concept of solving their problems and am not above using a less open solution than what might otherwise find if think it is worthwhile for the customer s VOI view this as a 36 november 2007 www linuxjournal com tactical solution although the strategic and long term solu tion may still be FOSS This even might lead to me advocating a Solaris solution for my customer But this is what I as the solution provider work out with my customer On the opposite side being a Linux Guy also means that when engage Sun as a supplier of Linux servers for my customers want to feel safe that can turn my back for a moment and not ha
119. fore such libraries catch up McCool Simply parallelizing the standard library functions would not have the same benefit because they do not individually do enough work RapidMind programs in contrast can do an arbitrary amount of user specified parallel computation Although RapidMind looks like a library to the developer it s important to realize that most of the work is done by the runtime platform The challenge facing multicore developers is not one that can be solved solely with libraries Developers need a system that efficiently takes care of the complexities of multicore 66 november 2007 www linuxjournal com For the same effort you can use RapidMind not only to get significantly higher performance on the same multicore processors you re already targeting but you can leverage the additional performance of accelerators as well processor specific optimization data manage ment dynamic load balancing scaling for additional cores and multiple levels of paral lelization The RapidMind platform performs all of these functions LJ You support multiple platforms on differ ent levels For example you can exploit the processors on NVIDIA and ATI graphics cards the Cell processor as well as multicore CPUs In addition you support both Linux and Windows correct DePaul The processor vendors are delivering some exciting and disruptive innovations Software companies are faced with some tough choices which v
120. from a certain date or deter mining the day on which a certain date falls countless scenarios need a routine to compute and display the date and time in the past or future searched for a suitable program but ultimately had to write one myself This program is called showdate It is written in the C language originally on UNIX and has been ported over to Linux as well You can download the code from the LJ FTP site ftp linuxjournal com pub lj listings issue163 9877 tgz After obtaining the source code assemble the showdate executable using an ANSI C compiler either cc or gcc as shown i cc showdate c o showdate Store the executable in usr local bin or a directory of your choice and invoke it without any arguments to obtain usage 4 showdate usage showdate y years m months d days h hours M minutes s seconds e f format showdate recognizes the following command line options and arguments B y 4 years Number of years in the past or future offset from the current year B m months Number of months in the past or future offset from the current month B d days Number of days in the past or future offset from the current day h Jhours Number of hours in the past or future offset from the current hour B M minutes Number of minutes in the past or future offset from the current minute B s
121. ful on Windows yet We ll consider your desires for the next ULB issue though Ed Protection Money have to congratulate you on your var opinion The Benevolent Racketeer LJ August 2007 Your imaginary letter writer speaks right out of the soul of everybody The crowd reading the lines will equally agree and see their points addressed as the crowd reading between the lines Luckily paid my insurance money to Linux Journal so you will not sue me for reading this terrific piece of word code Kurt mkdir Errors too have a small nit to pick with respect to sample code and the lack of error handling It is trivial to add at least some minimal error handling In the September 2007 issue s Letters Jack points out that mkdir error handling is non existent Bash scripts are notorious for not doing any error handling As for the mkdir issue that Jack points out would suggest the following mkdir p dimension if ne 0 then echo Error could not create directory dimension return 1 11 The p switch to mkdir will create all directories in the dimension string recursively and will not complain if any or all directories already exist The main reason for failure will be user permis sions This is handled by echoing the error and returning an error value to the caller If the goal of these sample scripts is to instruct beginners to learn techniques with bash error handling cannot be ignored Th
122. game more realistic and more difficult if you so choose For instance you can decide what effect speed has on steering by adjusting a slider to a desired percentage The higher the percentage the more difficult it is at high speeds You also can choose to map different keys for the gas pedal brakes and steering Shifting and clutch controls can be defined as well confess that I found it much easier to set up to use an automatic transmission on my first few races That brings up another point make sure you are in gear before you start It took me a few tries before I realized that was going backward Press the S key to start then press 1 to get in gear If you have selected automatic shifting will happen automatically for you after this There are more options and settings which I ll let you discover but do want to mention one other group of settings that may be important Given that this an OpenGL game and that it does require hardware 3 D acceleration owners of somewhat less powerful video cards may find the game more responsive by toning down some of the effects As you race you can change your viewing angle by pressing F1 through F5 If you find yourself totally taken with the action on screen and you feel the desire to pre serve the moment you can get a screenshot of the action at any time by pressing F12 Those images will appear in the folder vdrift screenshots in your home directory The final item on tonight s menu
123. gest and best business partner the Linux community including Linux VARs and Linux resellers Just as ships no longer use marine chronometers and sextants to follow the Sun but use GPS systems instead companies no longer guide their businesses with half baked marketing statements Sun s marketing group needs to understand that this is no longer the time of sailing ships and dead reckoning You can not just start from where you have been and hope to end up where you want by setting some course and sailing full steam ahead You will find yourself on the rocks The product era of computer science is sinking and now the era of service oriented computing is well underway Sun s marketing and business practices need to move into the 21st century and Sun needs a new vision for how it is going to provide solutions for its customers and partners and move the company forward really hope Sun finds Jon maddog Hall is the Executive Director of Linux International www li org a nonprofit association of end users who wish to support and promote the Linux oper ating system During his career in commercial computing which started in 1969 Mr Hall has been a programmer systems designer systems administrator product manager technical marketing manager and educator He has worked for such com panies as Western Electric Corporation Aetna Life and Casualty Bell Laboratories Digital Equipment Corporation Linux Systems and 561 He i
124. go We reproduced the bug and our tool dutifully reported the actual location of where the race condition happened lines 37 and 38 Things go wrong when two threads find prime numbers and they try to update the primes array and total variable a textbook example of a race condition But it s pretty easy to fix We have to serialize threads entering these two lines of code Can we do that with OpenMP Sure we can 37 pragma omp critical 38 39 primes total i 40 Lotal With that let s see what the final speedup is going to be 84 november 2007 www linuxjournal com cc fast xloopinfo xautopar xopenmp prime c o prime collect prime 2000000 Creating experiment database test 4 er Number of prime numbers between 2 and 2000000 148933 er print statistics test 4 er grep Duration Duration sec 1 138 It s 2 95 times faster Not bad for 15 minutes of work and four extra lines of OpenMP pragmas giving hints to the compiler A Few Loose Ends OpenMP and xautopar seem to work pretty well for C but what about C Will they mesh well with the kind of modern C usage peppered with generics and template metaprogramming The short answer is there s no short answer But let s see for ourselves with the following example of modern C ab use include lt vector gt include lt iterator gt Resources Moore s Law www intel com technology mooreslaw index htm Sun Studio Express developers sun com s
125. ha d authkeys File auth 1 1 shal ThisIsAVeryLongAndBoringPassword The ha cf File The next file to configure is the ha cf file the main Heartbeat config uration file The contents of this file should be the same on all nodes with a couple of exceptions Heartbeat ships with a detailed example file in the documenta tion directory that is well worth a look Also when creating your ha cf file the order in which things appear matters Don t move them around Two different example ha cf files are shown in Listings 2 and 3 The first thing you need to specify is the keepalive the time between heartbeats in seconds generally like to have this set to one or two but servers under heavy loads might not be able to send heartbeats in a timely manner So if you re seeing a lot of warnings about late heartbeats try increasing the keepalive The deadtime is next This is the time to wait without hearing from a cluster member before the surviving members of the array declare the problem host as being dead Next comes the warntime This setting determines how long to wait before issuing a late heartbeat warning Sometimes when all members of a cluster are booted at the same time there is a significant length of time between when Heartbeat is started and before the network or serial interfaces are ready to send and receive heartbeats The optional initdead directive takes care of this issue by setting an initial deadtime that applies List
126. halt command As a result of this system crash the RHEL cluster events were triggered and the MySQL database automatically restarted on Commsvr2 This whole failover process took one to two minutes and happened quite seamlessly Summary RHEL clustering technology provides a reliable high available infrastructure that can be used for meeting 24 7 business require ments for databases as well as legacy applications The most important thing to remember is that it is best to plan carefully before the actual implementation and test your cluster and all possible failover scenarios thoroughly before going live with a RHEL cluster A well documented cluster test plan also can be helpful in this regard Khurram Shiraz is senior system administrator at KMEFIC Kuwait In his eight years of IT experience he has worked mainly with IBM technologies and products especially AIX HACMP Clustering Tivoli and IBM SAN NAS storage He also has worked with the IBM Integrated Technology Services group His areas of expertise include design and implementation of high availahility and DR solutions based on pSeries Linux and Windows infrastructures He can be reached at aix_tiger yahoo com www linuxjournal com november 2007 51 betting 5tarted with Heartbeat Your first step toward high availability bliss Daniel Bartholomew 52 november 2007 www linuxjournal com In every work environment with which I have been involved certain servers
127. hanged and next time our award winning cellar will once again be open But for now Francois will pour you another beer that you may enjoy at your leisure while you enjoy another race Remember mes amis that sitting in front of your Linux systems driving a virtual car is the only way to drink and drive safely Raise your glasses mes amis and let us all drink to one another s health A votre sant Bon app tit W Marcel Gagn is an award winning writer living in Waterloo Ontario He is the author of the all new Moving to Free Software his sixth book from Addison Wesley He also makes regular television appearances as Call for Help s Linux guy Marcel is also a pilot a past Top 40 disc jockey writes science fiction and fantasy and folds a mean rigami T Rex He can he reached via e mail at mggagne salmar com You can discover lots of other things including great Wine links from his Web site at www marcelgagne com Resources ManiaDrive maniadrive raydium org SuperTuxKart supertuxkart berlios de VDrift vdrift net 5 Web Site www marcelgagne com The WFTL LUG Marcel s Online Linux User Group www marcelgagne com wftllugform html Polywell s Ultimate Linux Systems More Choices Excellent Support Service Great Value 1U Value Servers Starts at 399 Up to 8GB RAM 399 1U 485Ax Sempron 3000 1GB DDR2 80GB HD For Volume Purchase Only 499 1U 485Ax Athlon64 3500 2GB DDR2 80GB HD For Volume Purchase O
128. hat with the right compiler it 5 possible But before we go there let s remember the third step from our three step parallelization program and establish a performance baseline cc fast prime c o prime collect prime 2000000 Creating experiment database test l er Number of prime numbers between 2 and 2000000 148933 er print statistics test 1l er Execution for entire program Start Label Total End Label Total Start Time sec 0 028 End Time sec 3 364 Duration 5 3 336 Total LWP Time sec 3 337 Average number of LWPs 1 000 The fast command line option instructs the Sun Studio C compiler to generate the fastest possible code for the same architecture where the compilation happens The last two commands actually run the 82 november 2007 www linuxjournal com generated executable and report runtime statistics for the function main Now we know that whatever we do to the source code the result shouldn t be slower than 3 336 seconds With that in mind let s try asking the compiler to do its best not only at identifying parallelism xloopinfo but at expressing it as well xautopar cc fast xloopinfo xautopar prime c o prime prime c line 14 not parallelized Loop has multiple exits prime c line 14 not parallelized loop has multiple exits inlined loop prime c line 31 PARALLELIZED and serial version generated prime c line 35 not parallelized unsafe dependence
129. he case of this project one of the elements I m using is a www linuxjournal com november 2007 89 Lcd View Select Add Node mmm Figure 4 Basic Composite Nodes Setup Figure 5 The Viewer Node and Window 3 D scene in Blender so retain this node and assign it to my primary camera Figure 4 Next split the bottom view into two windows and in the right most pane pull up the image editor window where there is a list box that allows you to choose the output nodes from the compositor window This is how you check your progress Figure 5 Next add a few more sources In each case pressing space brings up a menu that allows me to add nodes want three addi tional input nodes and from each assign the appropriate type For this project I m working with two still images the lens flare and the background photo and one image sequence the greenscreen clip rendered out from DV to an image sequence to make it easier to work with First build the nodes chain for the background image Figure 6 The first node moving left to right is our source node the photo itself The second is a scale node which use to shrink my rather large digital photograph down to something approximat ing SD video resolution Next l ve used an RGB curves node to blow the highlights out of the photo to help sell the illusion that our character is looking from a shaded courtyard out into a wild garden in direct su
130. here the user data resides Without clustering shared storage or additional software components such as a proxy server multiple mail store servers cannot share the same IMAP POP3 process load under a unified service namespace Because of this using a single mail store server tends to be an obvious solution However one node usually implies elevated server hardware expenses when more powerful server hardware needs to be purchased to accom modate the ever increasing system load The price of a mid range server with four CPUs is usually much higher than the total price www linuxjournal com november 2007 57 FEATURE Building a Scalable High Availability E Mail System with Active Directory amp More SMTP IMAP POP3 IMAPs POP3s Postfix 3 Postfix m u E E go Cyrus Proxy Cyrus Proxy SAN Figure 4 Cyrus IMAP Aggregation Setup of three or more entry class servers Furthermore a single node architecture reduces system scalability and creates a single point of failure The Cyrus IMAP package is proven to be robust and suitable in large settings It differs from other Maildir or mbox IMAP servers in that it is intended to run as a sealed mailbox server the Cyrus mailbox database is stored in parts of the filesystem that are private to the Cyrus IMAP system More important a multiple server setup using Cyrus Murder aggregation is supported It scales out the system s load by using multiple front end IMAP proxie
131. hey snorted coke and bought mansions That s OK with me and it still works for some But the data is written on the wall and it is an age old warning that applies to all adapt or die Readers may wonder what all this has to do with cell ohone networks Carl Brown suggest ed that there is nothing fundamentally block ing the concept of a user created cell phone network It also is true that there is nothing blocking users from building their own world wide data network uncontrolled by govern ments or corporations If can share my Wi Fi with the neighbors in my apartment can bridge to the guy across the street who can run a directional shot to his buddy a quarter mile away who can ad infinitum The idea was not invented by me although I humbly declare thought of it myself The idea is so obvious anyone with an understanding of networks is likely to conceive of it A quick Google search brings to light that user operated and user supported community networks are already providing free service to many people The ISPs don t like it but there s nothing they can do about it Those simple networks howev er are only attachments to the Internet They still depend on the corporate infrastructure Another and related sign of the trend toward anarchy is revealed in the project called Netsukuku netsukuku freaknet org That project community has created a daemon that uses network interfaces to communicate directly with the s
132. hosts if you don t have internal DNS 197 168 98 125 192 168 890 179 localhost The order of the hosts is extremely important distcc is unable to determine which hosts are more powerful or under less load and simply distributes the compile jobs in order For jobs that can t be run in parallel such as configure tests this means the first host in the list will bear the brunt of the compiling If you have machines of varying power it can make a large difference in compile time to put the most powerful machines first and the least powerful machine last on the list of hosts Depending on the power of the computer running distcc you may not want to include localhost in the list of hosts at all Localhost has to do all of the preprocessing a deliberate design choice that means you don t need to ensure that you have the same set of libraries and header files on each machine and also all of the linking which is often hugely processor intensive on a large compile There is also a certain small amount of processing overhead in managing shipping the files around the network to the other compilers As a rule of thumb the distcc documentation recommends that for three to four hosts localhost probably should be placed last on the list and for greater than five hosts it should be excluded altogether Now that you have your cluster configured compiling is very simi lar to how you would have done it without distcc The only real differ ence is th
133. hould get here only after we write out everything return 0 other headaches as well Most notably the TCP TIME_WAIT state has a timeout of twice the maximum segment lifetime Because the round trip time varies widely in busy networks and networks with high latency oftentimes this value will be inaccurate There are other problems too but if you design your application well with proper protocol headers and PDU boundaries there never should be a need to use different TCP connections Take the case of SSH for instance How many different TCP streams are multiplexed with just one connection Take a cue from it You don t have to work in lockstep between the client and the server Simply because the protocols and algorithms are visualized in a fixed sequence does not imply that the implementation should follow suit ASA COMPUTERS Hardware Systems for the open source community Since 1989 Linux FreeBSD NetBSD OpenBSD Solaris MS etc The AMD Opteron processors deliver high performance scalable server solutions for the most advanced applications Runs both 32 and 64 bit applications simultaneously Your Custom Applicance Solution Let us know your Needs We will build you a Solution Opleron TM Value Server Staris al 1U 14 Deep 260W AMD Opteron 140 CPU 512MB PC 3200 DDR ECC Unbuffered Support upto 858 DDR RAM 40GB SATA Hard Disk 2x 10 1000 Mbps Lan EE ec oc 1U AMD
134. ia might clear things up A car is said to be drifting when the rear slip angle is greater than the front slip angle and the front wheels are pointing in the opposite direction of the turn In other words the car is turning one way but the wheels are pointing in another direction This strange as it may seem this is not an accident Remember the driver is in control As the driver what you are doing is sliding into a turn to avoid slowing down as much as possible When the game starts you can select the car you want and in some cases the color Where you race is another option Choose a racetrack or go for a relaxing high speed Single Race a Figure 5 VDrift lets you select from several different cars colors and racing venues COLUMNS polu imm baal 0 060 Figure 6 Yes it is exactly what it looks like There is a huge gap in the road Hammer down jump keep it straight and keep your cool COOKING WITH LINUX checkpoints lap I fom drive in the country Practice races put you on the track with no other cars to worry about Races pit you against an opponent On a single computer you can play VDrift alone or against a computer opponent at which point you also can decide on your opponent s car model and color Figure 5 VDrift also can be run as a server at which point your friends can join in for a networked game Several option controls exist to make the
135. ica tions which spawned the first generation of APIs that made it possible to read and write your data Facebook is the first of the new generation of Web sites that look at themselves as a platform more than an application And although Amazon Google and eBay have demonstrated the importance and potential of a platform centric view Facebook is pioneering the incorporation of third party applications True most Facebook applications created to date are simple or trivial But we can expect that these applications will become increasingly sophisti cated and useful over time Facebook s willingness to open up to third party developers is good for everyone except for competing sites such as MySpace and Linkedln which still appear to see themselves as standalone sites rather than platforms for new applications This month explained why find Facebook s API to be new and exciting Next month we ll look at how you can create your own Facebook applications Even if you aren t interested in creating applications for Facebook you owe it to yourself to see how the latest generation of Web applications allow themselves to be modified not just queried Reuven M Lerner a longtime Web database developer and consultant is a PhD candidate in learning sciences at Northwestern University studying on line learning communities He recently returned with his wife and three children to their home in Modi in Israel after four years
136. iewer allowing for example a manager to get a sense of what and how much employees are getting done each day Read Write Protocols The idea that a Web site could provide a regularly updated machine parseable version of its content whetted the appetite of many developers for more Many developers wanted a method to add and modify data as well as retrieve it This came in several different forms all of which still are used today The first was XML RPC a simple RPC protocol that used HTTP to send an XML encoded func tion invocation on a remote server The server turned the XML RPC request into a local function call and sent the result of that call or an error message in an XML encoded response The good news was and is that XML RPC is simple to understand and use that there are implementations in many different languages and that they are generally compatible and interoperable At the same time XML RPC was unable to handle some of the more complex data types that people wanted to use Plus it didn t have the official seal of approval or complete standard that would have been necessary for it to enter the corporate arena So some of the original XML RPC developers created SOAP originally known as the Simple Object Access Protocol but now an acronym that doesn t expand SOAP is more sophisticated and complete than XML RPC but it had a great many issues with compatibility implementation and complexity Today there are SO
137. ike Frysinger the official maintainer of the Blackfin Watchdog driver Mike Sharkey of Pike Aerospace Research Corporation has volunteered to take over the otherwise unmaintained Parallel Port driver on behalf of his company And Anton Vorontsov recently became a co maintainer of the Power Supply subsystem along with David Woodhouse Over time various features have gone into the kernel to support more and more modern architectures But for some of these features that have no seri ous negative impact on older hardware such as the 386 processor there s been no real effort to isolate the unneeded features from that older hardware Kernels compiled for those systems therefore have tended to have larger and larger binaries and to require more and more RAM to run For the most part no one notices or cares because most people don t bother running Linux on the 386 anymore But the effect has been there building gradually Jonathan Campbell recently started submitting patches to ensure that architectures like the 386 would compile only features that actually would work on those systems So things like the Pentium TSC register would not be included in compiled 386 kernel binaries The result of his work was a much smaller binary and his patches probably will be adopted into the main kernel tree This kind of support for legacy systems might have an impact on projects to bring com puting resources to third world coun tries and
138. ilar but it requires the use of ssh keys Either passphraseless keys or an ssh agent must be used as you will be unable to supply a password for distcc to use For SSH connections distccd must be installed on the clients but it must not be listening for connections the daemons will be started 62 november 2007 www linuxjournal com over SSH when needed First create an SSH key using ssh keygen t dsa then add it to the target user s ssh authorized_keys on your distcc hosts It s recommended always to set a passphrase on an SSH key for security In this example I m using my own user account on all of the hosts and a simple bash loop to distribute the key quickly for i in 192 168 80 120 192 168 80 100 do cat ssh id dsa pub ssh jes i cat gt gt ssh authorized_keys done To let distcc know that it needs to connect to the hosts under SSH modify either the distcc hosts file or DISTCC HOSTS variable instruct distcc to use SSH simply add an to the beginning of the hostname If you need to use a different user name on any of the hosts you can specify it as user host localhost 0192 168 80 100 0192 168 80 120 Because I m using a key with a passphrase also need to start my SSH agent with ssh add and enter my passphrase For those unfamiliar with ssh agent it s a tool that ships with OpenSSH that facilitates needing to enter the passphrase for your key only once a session retaining it
139. impoverished neighborhoods or lower the cost of experimenting with clustered solutions ZACK BROWN 12 november 2007 www linuxjournal com LJ Index November 2007 1 Average measured speed in MBps of a broadband connection with up to 8Mbps download speed 2 7 2 Lowest measured speed in KBps of a broadband connection with to 8Mbps download speed 90 3 Number of consumers out of five who get the broadband speed they signed up for 1 4 Percent of surveyed consumers who have felt misled by providers advertising 30 5 Billions of Internet users in 2006 1 1 6 Additional millions of Internet users expected by 2010 500 7 Millions of video streams per day served by YouTube 100 8 Number of surveillance cameras in London 200 9 Trillions of bits sent by London surveillance cameras to their data center 64 10 Terabytes accumulated per day by Chevron 2 11 Total exabytes of data in 2006 161 12 Multiple in millions of 2006 data total to all information in all books ever written 3 13 Percentage of the digital universe that will be created by individuals by 2010 70 14 Percentage of the current digital universe that is subject to compliance rules and standards 20 15 Percentage of the current digital universe that is potentially subject to security applications 30 16 Exabytes of user generated content expected by 2010 692 17 Total exabytes of data expected by 2010 988
140. in SuperTuxKart are fun colorful and imaginative Race though an undersea lair through the shifting sands of the Egyptian desert or around obstacles in Oliver s Math Glass And don t worry too much about falling off the edge of the world or an altogether psychedelic cliff Your jumping flying car will carry you back to safety using its combination magnetic levitation system and butterfly wings The next item on tonight s menu is a great racing Note All these packages are available as source code bundles from their respective Web sites Before you start compiling unless you want to of course check your distribution s software repositories for binary packages In all cases had no trouble finding packages 28 november 2007 www linuxjournal com yi mrt ow P mm Figure 4 On the Track with VDrift against a Computer Player game called VDrift Created by Joe Venzon VDrift is an exciting game based on drift racing The V in VDrift refers to the Vamos Automotive Simulator written by Sam Varner Vamos is the physics engine that powers the game Aside from being exciting and great fun to play VDrift comes with 19 world class tracks and 28 different car models VDrift is available at vdrift net In case you don t know what drift racing is your humble Chef did not it s a form of racing where the driver employs drifting to control the car Doesn t help Well this quote from Wikiped
141. in memory Now that we ve set up SSH keys and told distcc to use a secure connection the procedure is the same as before simply make jn Other Options This method of modifying the hostname with the options you want distcc to honour can be used for more than specifying the connection type For example the option limit can be used to override the default number of jobs that will be sent to the distccd servers The original limit is four jobs per host except localhost which is sent only two This could be increased for servers with more than two CPUs Another option is to use 20 compression for either TCP or SSH connections This increases CPU overhead but it may be worthwhile on slow networks Combining these two options would be done with localhost 192 168 80 100 6 1zo This option increases the jobs sent to 192 168 80 100 to six and it enables use of 20 compression These options are parsed in a specific order so some study of the man page is recommended if you intend to use them A full list of options with examples can be found on the distcc man page The flexibility of distcc covers far more than explained here One popular configuration is to use it with ccache a compiler cache distcc also can be used with crossdev to cross compile for different architec tures in a distributed fashion Now your old SPARC workstation can get in on the act or your G5 Mac turned Linux box can join the party These are topics for future articl
142. in the Chicago area Expert Included Xeon Kim provides expert dedicated customer support for one of the most comprehensive server and storage product offerings in the industry Quad core Unmatched She is excited to introduce the new Rackform iServ R141 1U server because it brings exceptional power and cost effectiveness to an entry level server The R141 features the Quad Core Intel Xeon processor 3200 series which delivers energy efficient performance v and Intel s dependability With quad core performance to 8 GB of DDR2 memory and four hot swap SATA hard drives the R141 has the versatility to effectively serve d small businesses or be the core of a small high performance computing cluster gt When you partner with Silicon Mechanics you get more than a reliable Intel solution you get a support expert like Kim SiLicom MECHANICS Silicon Mechanics and the Silicon Mechanics logo are registered trademarks of Silicon Mechanics Inc Intel the Intel logo Xeon and Xeon Inside spa aban Ss educi 117 0 are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries m x COLUMNS MARCEL GAGN COOKING WITH LINUX Because Nothing Says High Performance Like a Good Race Got Linux Got a good accelerated video card as well Then get behind th
143. ing 2 The etc ha d ha cf File on Briggs amp Stratton deadtime 32 warntime 16 initdead 64 baud 19200 On briggs the serial device is dev ttyS1 On stratton the serial device is dev ttyS0 serial dev ttyS1 auto failback on node briggs node stratton use logd yes Listing 3 The etc ha d ha cf File on Deimos amp Phobos deadtime 10 warntime 5 udpport 694 deimos heartbeat ip address is 192 168 1 11 phobos heartbeat ip address is 192 168 1 21 ucast etl 192 16995111 auto failback off stonith_host deimos wti_nps ares example com erisisihekey stonith_host phobos wti_nps ares example com erisIsTheKey node deimos node phobos use logd yes www linuxjournal com november 2007 53 FEATURE Getting Started with Heartbeat only when Heartbeat is first started You can send heartbeats over serial or Ethernet links either works fine like serial for two server clusters that are physically close together but Ethernet works just as well The configuration for serial ports is easy simply specify the baud rate and then the serial device you are using The serial device is one place where the ha cf files on each node may differ due to the serial port having dif ferent names on each host If you don t know the tty to which your serial port is assigned run the following command setserial g dev ttyS If anything in the output says UART unknown that device is
144. ing SLED preloaded and supported on its business oriented ThinkPad T Series Lenovo says that strong demand for Linux notebooks from customers made the preload option inevitable Preloaded ThinkPads will be available to the general public in Q4 2007 www lenovo com linux Storix Inc s SBAdmin Em Storix Inc recently released SBAdmin v6 2 touted as the first backup and system recov ery solution to integrate with IBM s Tivoli Storage Manager TSM SBAdmin complements TSM s features and capabilities for Linux and AIX systems SBAdmin also writes directly to the TSM server which cuts extraneous steps saves time and increases reliability In addition the application provides TSM users with disaster recovery capabili ties including a feature called Adaptable System Recovery which enables a system restore to the same or dissimilar hardware www storix com Motorola s MOTOMAGX Mobile Linux Platform In the near future Motorola expects 60 of its handsets to run on Linux and the new MOTOMAGxX platform is a means for realizing that goal Motorola calls its next generation mobile Linux platform that MOTOROLA will deliver new levels of openness flexibility and support for third party applications on its devices The company also hopes to empower its developer community to innovate in exciting ways Currently MOTOMAGX supports apps developed in Java ME and will soon support WebUI and native Linux applic
145. ing System 7 see Wikipedia is a standard for control signaling in the PSTN Public Switched Telephone Network SS7 signaling is done out of band meaning that SS7 signaling mes sages are transported over a separate data connection This repre sents a significant security improvement over earlier systems that used in band signaling SCTP basically was invented to handle pro tocols like SS7 over IP SS7 uses multihoming to increase reliability and streams to avoid the TCP problem of head of line blocking Diameter RFC 3588 www rfc editor org rfc rfc3588 txt is IETF protocol to supply an Authentication Authorization and Accounting AAA framework for applications such as network access or IP mobility A good introduction is at www interlinknetworks com whitepapers Introduction to Diameter pdf It replaces an earlier protocol Radius that ran over UDP Diameter uses TCP or SCTP for the added reliability of these transports A Diameter server must support both TCP and SCTP although at present clients can choose either SCTP is the default and in the future clients may be required to support SCTP SCTP is preferred because it can use streams to avoid the head of line blocking problem that exists with TCP DLM Distributed Lock Manager sources redhat com cluster dlm is a Red Hat project currently in the kernel This can use either TCP or SCTP SCTP has the advantage of multihome support Although TCP presently is the default SCTP c
146. ion and it has its own Kerberos implementation for authentication The goal of an integrated AD authentication is to allow the Linux e mail servers to use AD to verify user credentials The technology used to support the AD integration scheme is based mainly on the Kerberos and LDAP support which come with native Linux components as shown in Figure 5 Here is how it works First we use AD Kerberos to authenti cate Linux clients Pluggable Authentication Module PAM is con figured to get the user credentials and pass them to the pam krb5 library which is then used to authenticate users using the Linux Kerberos client connection to the Key Distribution Center KDC on Active Directory This practice eliminates the need for authenti cation administration on the Linux side However with only the Kerberos integration Linux has to store authorization data in the local etc passwd file To avoid managing a separate user authorization list LDAP is used to retrieve user authorization informa tion from AD The idea is to let authorization requests processed by Name Service Switch NSS first NSS allows the replacement of many UNIX Linux configuration files such as etc passwd etc group and etc hosts with a centralized database or databases and the mechanisms used to access those databases are configurable NSS then uses the Name Service Caching Daemon NSCD to improve query performance NSCD is a daemon that provides a cache for the
147. ions As a result administrative tools are able to install and manage the system as a whole rather than as individual workstations or servers These tools continue to get easier to use enabling users with limited technical skills to jump quickly into HPC To take just one example Linux Networx recently launched its newest cluster management application Clusterworx Advanced This application provides system administrators with intuitive tools that greatly simplify operations and reduce administration workload Third Linux based clusters are easy to scale due in part to newer filesystems such as GPFS and Lustre which provide better scalability but only on Linux and UNIX Windows based filesystems are typically tuned for file sharing and don t provide the type of performance and accessibility required when lots of compute nodes all request the same dataset at the same time Fourth resource management tools such as Altair s PBS Pro and Platform LSF ensure that computing resources are being allocated with utilization rates exceeding 9096 Without proper resource management systems tend to work only when the engineering team works thereby limiting overall utilization With mature resource management tools such as those available for Linux based HPC systems jobs can be scheduled 24 hours a day 365 days a year Multiple jobs can be run simultaneously as needed thereby ensuring excess power is always put to use Fifth from a stability pe
148. ited States and other countries For terms and conditions please see www aberdeeninc com abpoly abterms htm 11021 888 297 7409 www aberdeeninc com j021 NEW PRODUCTS ASUS Eee PC 700 701 Fear not gadget geeks for in future issues we ll fully cover the new ASUS Eee PC so much so that you ll grumble enough already The Eee PC is a new ultraportable Linux based laptop starting at this is not a typo 259 US ASUS is marketing the 700 model 2GB Flash storage 256MB of RAM to first time elderly computer users low income house holds and K 12 education while the 701 model AGB Flash storage 512MB of is mainly for PC owners seeking convenient mobility Both models feature preloaded Xandros Linux Intel Celeron M 900MHz processor 7 display 10 100Mbps LAN 802 11 b g wireless three USB 2 0 ports MMC SD card reader VGA out Windows compatibility drivers built in camera optional on the 700 s and a four cell battery There are no optical drives both models weigh in at 0 9kg 2lbs At the time of this writing ASUS projects that dealers should have the Eee PC by late September 2007 www asuseeepc com Lenovo s ThinkPad T Series Linux Notebooks A year ago we saw Lenovo tepidly dip its pinky toe into the Linux waters by certifying and supporting its ThinkPad T60p notebook with user installed SUSE Linux Enterprise Desktop SLED This year finds Lenovo frolicking in the balmy Linux Sea offer
149. ives they take this year Companies that choose to do nothing will quickly find themselves behind the performance curve Companies that embark on large complex multithreading projects will be frustrated with the costs and timelines and in the end largely disappointed with the outcome We are fortunate to be partnering with a group of software organizations that see an opportunity to deliver substantial performance improvements to their customers without a devastating impact on their software development cycles LJ Thank you so much for your time Nicholas Petreley is Editor in Chief of Linux Journal and a former programmer teacher analyst and consultant who has been working with and writing about Linux for more than ten years Growing World of Linux Professionals LPI Deutsch 7g PI France LPI Spain LPI Portugal 6 LPI Malta Cyprus LPI Latin America We at the Linux Professional Institute believe the best way to spread the adoption of Linux and Open Source software is to grow a world wide supply of talented qualified and accredited IT professionals We realize the importance of providing a global standard of measurement To assist in this effort we are launching a Regional Enablement Initiative to ensure we understand nurture and support the needs of the enterprise govern ments educational institutions and individual contributors around the globe LPI South Africa LPI Bulgaria We can only achieve
150. k Sushi the Octopus Figure 2 Yeti and others You Figure 2 SuperTuxKart features some colorful characters many with equally colorful names THE QUAD CORE PROCESSORS YOU VE BEEN LONGING TO SEE BEBMAAMEMEMUMMMMMML EE LJ 7 7 WEM BP LuEEMEMEMEMMMNMNMNMNUE PERFORMANCEWARE 1680 PERFORMANCEWARE 5870 SHOCKING PERFORMANCE amp RELIABILITY IN A JUNGLE OF MEDIOCRITY FIND OUT HOW MUCH HARD CORE COMPUTING POWER CAN BE WEDGED INTO COMPACT SERVERS Pogo Linux raises the bar again with the all new 4 way PerformanceWare 1680 and 8 way PerformanceWare 5870 with the new Quad Core AMD Opteron processors Quad Core AMD Opteron processors feature native quad core technology on a single piece of silicon so data can move between cores at full speed for more efficient data sharing AMD s revolutionary Direct Connect Architecture eliminates the bottlenecks inherent in traditional front side bus architectures for high throughput responsiveness and scalability to improve overall system efficiency Economical in size and price and built for the most demanding database applications high performance computing and server virtualization the PerformanceWare 1680 and PerformanceWare 5870 deliver Call Pogo today 7 v p 5 linux Experience Imagination and Support e Solutions Built for Linux Built for You Pogo Linux is Hardwz To get started contact us at 888 828 POGO or contact sale
151. l Fortunately with logging enabled troubleshooting is easy because Heartbeat outputs informative log messages Heartbeat even will let you know when a previous log message is not something you have to worry about When bringing a new cluster on line usually open an SSH terminal to each cluster member and tail the messages file like so tail f var log messages Then in separate terminals start up Heartbeat If there are any problems it is usually pretty easy to spot them Heartbeat also comes with very good documentation Whenever run into problems this documentation has been invaluable On my system it is located under the usr share doc directory Conclusion l ve barely scratched the surface of Heartbeat s capabilities here Fortunately a lot of resources exist to help you learn about Heartbeat s more advanced features These include active passive and active active clusters with N number of nodes DRBD the Cluster Resource Manager and more Now that your feet are wet hopefully you won t be quite as intimidated as was when first started learning about Heartbeat Be careful though or you might end up like me and want to cluster everything Daniel Bartholomew has been using computers since the early 1980s when his parents purchased an Apple After stints on Mac and Windows machines he discovered Linux in 1996 and has been using various distributions ever since He lives with his wife and children in North Car
152. l implementations of getsockopt The code is sctp assoc t get associd int sockfd struct sockaddr sa socklen t salen struct sctp paddrinfo sp int 2 57 sizeof struct sctp paddrinfo bzero amp sp sz memcpy amp sp spinfo address sa salen if sctp opt info sockfd 0 SCTP GET PEER ADDR INFO amp sp amp sz 1 perror get assoc return sp spinfo assoc id Note that Unix Network Programming volume 1 3rd ed by W Richard Stevens et al gives different code the specification has changed since that book was written and the above is now the pre ferred way and Stevens code doesn t work under Linux anyway Multiple Associations A server can handle multiple clients in a number of ways a TCP server can use a single server socket that listens for clients and deals with them sequentially or it could fork off each new client connection as a separate process or thread or it could have many sockets and poll or select between them A UDP server typically will keep no client state and will treat each message in its entirety as a separate entity SCTP offers another variation roughly halfway between TCP and UDP An SCTP socket can handle multiple long lived associations to many endpoints simultaneously It supports the connection oriented semantics of TCP by maintaining an association ID for each associa tion On the other hand it is like UDP in that each read usually returns a complete message from a
153. le and added the following line daemon var log cluster To apply this change I restarted syslogd with the service syslog restart command Another important step is to specify the time period for rotating cluster log files This can be done by specifying the name of the cluster log file in the etc logrotate conf file the default is a weekly rotation var log messages var log secure var log maillog var log spooler var log boot log var log cron var log cluster sharedscripts postrotate bin kill HUP cat var run syslogd pid 2 dev null 2 dev null true endscript You also have to pay special attention to keeping UIDs and GIDs synchronized across cluster nodes This is important in making sure proper permissions are maintained especially with reference to the shared data filesystem GRUB also needs to conform to the suite environment s specific needs For instance many system administrators in a RHEL cluster environment reduce the GRUB selection timeout to some lower values such as two seconds to accelerate system restart time Database Integration with a RHEL Cluster The same RHEL cluster infrastructure can be used for providing high availability to databases such as Oracle MySQL and IBM DB2 The most important thing to remember is to base your database related services on a shared IP address for example you have to configure Oracle listener based on the shared service IP address Next explain in
154. like one Several Guadec attendees compared Puppy with Sony s Aibo the most notable difference besides looks being the Puppy s openness It s a pure DIY pet make of him what you like Also Aibo had no eyes Puppy not only has eyes on his display but he also can look at the world through the N800 s built in camera which is in a barely noticeable black cylinder that pops out the side of the N800 It got confusing to take pictures of Puppy and Rover while they took pictures of me which appeared on other N800s over wireless connections Puppy and Rover s non N800 hardware is all from the Robotics com catalog The controlling software all open source is at https garage maemo org projects robot You also can see Puppy in action at youtube com puppyrobot DOC SEARLS If our customers buy bandwidth from us and they want to share it with neighbors or publicly that doesn t make them bad customers Joe Plotkin Bway net www businessweek com technology content jul2002 tc2002073_1130 htm the commercial concerns from the very beginning even when they were small were really very important The commercial distributions were what drove a lot of the nice installers and pushed people to improve usability think commer cial users of Linux have been very important in actually improving the product think all the technical people who have been involved have been hugely important but think that the kind of commercial
155. list of topics and due dates can be found on line www linuxjournal com author ADVERTISING Linux Journal is a great resource for readers and advertisers alike Request a media kit view our current editorial calendar and advertising due dates or learn more about other advertising and marketing opportunities by visiting us on line www linuxjournal com advertising Contact us directly for further information ads linuxjournal com or 1 713 344 1956 ext 2 ON LINE WEB SITE Read exclusive on line only content on Linux Journal s Web site www linuxjournal com Also select articles from the print magazine are available on line Magazine subscribers digital or print receive full access to issue archives please contact Customer Service for further information subs linuxjournal com FREE e NEWSLETTERS Each week Linux Journal editors will tell you what s hot in the world of Linux Receive late breaking news technical tips and tricks and links to in depth stories featured on www linuxjournal com Subscribe for free today www linuxjournal com enewsletters Maximize AMD Opteron Quad Core Performance with UniServer LIO CET TT 1U UniServer with 1 Socket e Dual Quad Core AMD Opteron 2000 series e Up to 32GB of memory e 2 hot swap SATA 3 5 HDDs e MCP55V Pro chipset Slim CD DVD ROM e 1 PCI Express x16 slot Remote management IPMI 2 0 1U Server 1 amp 2 Sockets up to 64GB memory 2U Serv
156. ll the m Mailed Through traditional 3 D modeling and animation tools are at the compositing Free Distribution Outside the Mail 2 343 m which i remel ful for anv number of Total Free Distribution 3 153 syste 50 Sposa ch is supremely useful for a u ibe O TED highly complicated shots that normally would require using several Copies Not Distributed 8 981 Total 57 908 Percent Paid and or Requested Circulation 9496 PS Form 3526 programs in conjunction to pull off correctly Here s hoping the Project Peach the currently in process sequel 94 november 2007 www linuxjournal com 1994 2006 ISSUES 1 152 of Linux Journal www LinuxJournal com ArchiveCD The 1994 2006 Archive CD back issues and more var opinion The demands of parallel processing may be met more easily in a language we already know Nick Petreley Editor in Chief had a wonderful experience chatting with the folks at RapidMind The company pro vides C C programmers with a very clever tool to help them exploit the parallel process ing capability of multiple core CPUs The idea is to make parallel processing at least somewhat transparent to the programmer Programmers can use RapidMind to improve multicore performance of existing applica tions with minimal modifications to their code and build new multicore applications without having to deal with all of the com plexities of things like thread synchronizatio
157. lly was designed for network programming and text processing This made it an obvious choice for Web pro gramming but Larry Wall certainly didn t know or expect that when he first wrote the language years before the Web was invented Users of a software package almost always will push its limits That s why some of the most successful and popular programs are those that encourage users to go beyond the author s imagination In the early days of the software industry such add ons and plugins didn t exist which meant that the only way to get new functionality was to lobby the authors and then hope the next release would include the needed features In the world of open source software anyone is theoretically able to add new features but between the generally small number of core developers and the famously loud debates that sometimes erupt it can take surprisingly long to add a new feature And although it is always possible to fork a project this has social and technical drawbacks that often outweigh the benefits Some programs have a long tradition of encouraging add ons GNU Emacs is best known as a text editor but it comes with a full fledged version of the Lisp programming language You can create just about anything you want in Emacs and people have done so including mail reading programs Web browsers and an extremely sophisticated calendar diary Photoshop caught on among graphic designers not only because of its powerful imag
158. luster Configuration Tool used to configure the cluster and display the current status of the nodes resources fencing agents and cluster services graphically Contains an interface library for cluster lock management and required plugins Contains the libraries used to identify the filesystem or volume manager in which a device is formatted techniques that can be used by the RHEL cluster for ensuring data integrity in concurrent access environments The traditional way is the use of CIVM which works well in most RHEL cluster implementations with LVM based logical volumes Another technique is GFS GFS is a cluster filesystem that allows a cluster of nodes to access simultaneously a block device that is shared among the nodes It employs distributed metadata and multiple journals for optimal operation in a cluster To maintain filesystem integrity GFS uses a lock manager DLM or GULM to coordinate I O When one node changes data on a GFS filesystem that change is visible immediately to the other cluster nodes using that filesystem Hence when you are implementing a RHEL cluster with concurrent data access require ments such as in the case of an Oracle RAC implementation you can use either GFS or CLVM In most Red Hat cluster implementa tions GFS is used with a direct access configu ration to shared SAN from all cluster nodes However for the same purpose you also can deploy GFS in a cluster that is connected to a
159. m rightsideup blogs com my weblog 2007 08 beyond the pers html He writes Our modern commercial setup is organised around a persuasion paradigm where the driving force in commerce is companies and their attempts to persuade individuals so called consumers to buy their products or services and not those of their rivals We are however groping our way towards a personal decision making paradigm whose 40 november 2007 www linuxjournal com centre of gravity is helping individuals make and implement better decisions at lower cost where cost includes time and hassle cost as well as money cost This is being made possible by an information age our increasing ability to search for gather store filter edit slice and dice analyze share the information we need to for our decision making Better personal decision making and implemen tation is an era defining shift for two simple reasons it shifts the focus of value creation from companies and their goals to individuals and their goals and it encompasses all aspects of production distribution and exchange and a whole lot more There is in this a declaration of independence for individuals in heed of the need to equip human beings with better ways to learn to make choices and to exercise their autonomy What s not clear and needs to be is the role played by programmers in equipping everybody with the freedom to escape the old persua sion paradigm a
160. me cases it is even harder if you want to take a huge existing application and adapt it for multiple cores So figured the real breakthrough is likely to be years away It seems as if RapidMind has a solution this problem that doesn t require a massive overhaul of an existing application and its solution is already available We invited RapidMind s President and CEO Ray DePaul and Founder and Chief Scientist Michael McCool to talk about RapidMind s approach to exploiting the power of multicore systems We deemed it important to look at RapidMind because it seems as if we re finally entering the age of parallel processing on the desktop as chip manufacturers bump up against the practical limits of Moore s Law Everything from graphics cards to PlayStation 3 consoles exploit parallel processing these days have an Intel quad core processor in my workstation Although I m happy with it find that the only time I truly appreciate having this multicore chip is when I run multiple applications simultaneously or run multiple processes such as with the command make j 5 If anything single threaded applications run slower on this chip than on the single core CPU used to run because each core in the Intel chip is significantly slower 2GHz vs 3GHz So how does RapidMind bridge the gap between existing software and the changing computational model LJ Could you give us a brief description of RapidMind and the problem it is designe
161. most common name service requests This can be very impor tant when used against a large AD user container Finally NSS LDAP is configured to serve as an LDAP client to connect to Active Directory to retrieve the authorization data from the AD users container NSS LDAP developed by PADL is a set of C library extensions that allow LDAP directory servers to be used as a primary source of aliases ethers groups hosts networks protocol users RPCs services and shadow passwords Now with authorization and authentication completely integrated with AD using both LDAP and Kerberos no local user credentials need to be maintained In order to support LDAP authorization integration with Linux Windows Server 2003 Release 2 R2 which includes support for RFC 2307 is installed on each of the AD domain controllers R2 introduces new LDAP attributes used to store UNIX or Linux user and group information Without an extended AD LDAP schema like the one used by R2 the Linux automatic authoriza tion integration with AD is not possible It is also important to mention that the SASL Authentication layer shown in Figure 3 is using Cyrus SASL which is distributed as a standard package by Carnegie Mellon University The actual setup uses PAM for authenticating IMAP POP3 users It requires the use of a special Cyrus daemon saslauthd which the SASL mechanism uses to communicate via a Linux named socket Conclusion Our new e mail system is mostly bas
162. n RapidMind and any other solutions like it are invaluable and will remain so for a long long time C C is an extremely well entrenched legacy programming platform can t help but wonder however if the trend toward increased parallel processing in hardware will create a slow but steady shift toward inherently multithreaded managed programming platforms like Java The inherent trade off to adding cores to a CPU poses an interesting problem for any programming platform As you add cores you increase power consumption which generates more heat One way to reduce heat is to lower the processing speed of the individual cores or at the very least keep them from advancing in speed as quickly as they might have if history could have continued along its current path As a result any single thread of execu tion would run faster on a speedy single core CPU than it would on a slower core of a multicore CPU The seemingly obvious answer is to split up the task into multiple threads Java is multithreaded by nature right Therefore all other things being equal a Java application should be a natural for multicore CPU platforms right Not necessarily If Java was a slam dunk superior way to exploit parallel processing would have posed this shift to Java as a predic tion not a question It s not that simple For example don t let anyone tell you that Java was built from the ground up to exploit multiple processors and cores It
163. n from an inetd If distccd is started as an unprivileged user account it will retain ownership by that UID If it is started as root it will attempt to change to the distcc or nobody user If you want to start the daemon as root perhaps from an init script and change to a user that is not distcc or nobody the option user allows you to select which user the daemon should run as distccd user jes allow 192 168 80 0 24 In this example also use the allow option This accepts a hostmask in common CIDR notation and restricts distcc access to the hosts specified Here restrict access only to servers on the particular subnet I m using on my home network machines with addresses in the 192 168 80 1 192 168 80 254 range If you are particularly security conscious you could restrict it to a single address 192 168 80 5 or any range of addresses supported by this notation like to leave it pretty loose because often change which host is the master depending on what I m compiling and when Compiling Back on the master system on which you plan to run your compiles you need to let distcc know where the rest of your cluster is There are two ways of achieving this You can add the hostnames or IP addresses of your cluster to the file distcc hosts or you can export the variable DISTCC HOSTS delimited by whitespace These names need to resolve either add the names you want to use to etc hosts or use the IP addresses of the
164. n outage longer than half a second not bad for two old castaways The cluster defined in Listings 3 and 5 is a bit more complicated This is the NFS cluster administer at work This cluster utilizes shared storage in the form of a pair of Coraid SR1521 ATA over Ethernet drive arrays two NFS appliances also from Coraid and a STONITH device STONITH is important for this cluster because in the event of a failure need to be sure that the other device is really dead before mounting the shared storage on the other node There are five resources managed in this cluster and to keep the line in haresources from getting too long to be readable break it up with line continuation slashes If the primary cluster member is having trouble the secondary cluster kills the primary Listing 4 A Minimalist haresources File Stratton 152 169 1 Al 3pache2 Listing 5 A More Substantial haresources File deimos 1 12 I5 Filesystem dev etherd el 0 opt storage xfs killnfsd nfs common nfs kernel server takes over the IP address mounts the shared storage and then starts up NFS With this cluster instead of having mainte nance issues or other outages lasting several minutes to an hour or more outages now don t last beyond a second or two can live with that Troubleshooting Now that your cluster is all configured start it with etc init d heartbeat start Things might work perfectly or not at al
165. n this genre probably have an equally bright future B Nicholas Petreley is Editor in Chief of Linux Journal and a former programmer teacher analyst and consultant who has been working with and writing about Linux for more than ten years Fanatical Support saved from my own mistake Not long ago reformatted one of our servers Not until was driving home did learn that brought our entire site down in the process called my guy at Rackspace and he said We re already on it By the time pulled in the driveway my site was back up Now that s Fanatical Support Keeping little mistakes from causing big problems is one definition of Fanatical Support What will yours be Watch Russ s story at www rackspace com fanatical 1 888 571 8976 rack MANAGED BHOSTING Em a TriCom DDR SDR InfiniBand HCA Switchless serial console NodeWatch web enabled remote monitor and control Headers to fan tach lines voltages temperature probes 8051 BMC interface and PS On Off and MB reset serial console switch COM2 Internal connector RJ45 RS 485 422 Daisy chain connectors Mellanox InfiniHost III InfiniBand HCA InfiniBand connector ServaStor Extensible IB based storage building blocks Redundant and scalable Parallel file systems Open source software On line capacity expansion RAID 0 1 1E 3 5 6 10 50 To speak to an HPC expert call 508 746 7341 and ask
166. nacea After all even our simplistic usage of it was enough to introduce a bug It seems that collect prime 2000000 regardless of how we express parallelism what we need is a tool Creating experiment database test 3 er that would help us uncover concurrency bugs Number of prime numbers between 2 and 2000000 146764 know of two such tools freely available on Linux Intel Thread er print statistics test 3 er grep Duration Checker and Sun Studio Thread Analyzer And here s how you can Duration sec 1 132 use the latter one to combat data races note that we need an extra compile time command line option xinstrument datarace to No doubt 294 is an impressive speedup but how come we make thread analysis possible and that we have to ask collect for lost some prime numbers We now have 146 764 of them reported recording data race events by specifying r on instead of 148 933 Maybe the compiler was right in being conservative and not parallelizing that pesky loop Should we go cc fast xloopinfo xautopar xopenmp xinstrument datarace back and remove our OpenMP pragma Not yet Even though w prime c o prime we ve just caught a bug in our parallelized version of the same collect r on prime 2000000 application which only goes to show how easy it is to introduce Creating experiment database tha l er bugs and how much more important regression testing becomes when you try to parallelize anything we still are on
167. nal game hardware but expect that all PCs manufactured in the last ten 8 november 2007 www linuxjournal com years use more power and produce more waste heat Even a PIII might have cooling problems One thing that is not widely known is that a P4 will generally take more clock cycles than a PIII to complete a given amount of work a 1 5GHz P4 will often deliver the same performance as a 1GHz PIII If a machine is to run in a poorly ventilated space a is a significantly better option than a P4 Hard drives take as much as 5W when idling Use of other mass storage devices such as USB might reduce the power use for such a machine have a small stockpile of old machines for occasions when need a low power machine Russell Coker The Inevitable Descent into Anarchy The Linux OS is the most glamorous I m serious example of the trend toward data anarchy but Linux is only an outgrowth of a much bigger universe of collaborative software development that uses open source licenses and techniques to leverage the talents and creative impulses of hundreds of thousands of people worldwide Cheap MP3 players and P2P file sharing networks are another Direct evidence of the trend is plummeting CD sales as users swap CDs copy new ones file share and port their files to any device they want The efforts of the RIAA are becoming laughable as they sue a few unfortunates and scold the rest of the population from
168. nance suggests that Linux has had a long history in HPC the truth is that Linux clusters began replacing UNIX systems only six years ago The reason for such quick initial take up is due to the fact that Linux and open systems brought commodity hardware and software into what had previously been a proprietary systems market This change brought costs down significantly allow ing users at the high end to purchase more power at lower cost and opening the door for new users such as traditional product designers who were not able to afford closed proprietary systems The domina tion of Linux in the HPC market is so successful that market research firm IDC estimated Linux represented 6596 of the total HPC market by mid 2006 as compared to approximately 3096 for UNIX with addi tional growth projected The Top 500 list confirms that growth Challenges and Questions Linux is clearly the present of HPC but is it the future Microsoft contin ues to make advancements with its Windows Compute Cluster Server has plenty of cash on hand and is clearly capable from a business perspective of eating up market share In addition despite its well known flaws everyone has worked with and is familiar with Windows potentially making it a comfortable platform to new HPC users Complicating matters further is that despite their well earned market dominance high performance Linux clusters have in many cases earned a reputation for being difficult to build
169. nciation Elementary Principles of Composition 9 Make the paragraph the unit of composition one paragraph to each topic 10 As a rule begin each paragraph with a topic sentence end it in conformity with the beginning 11 Use the active voice 12 Put statements in positive form 13 Omit needless words 14 Avoid a succession of loose sentences 15 Express co ordinate ideas in similar form 16 Keep related words together 17 In summaries keep to one tense 18 Place the emphatic words of a sentence at the end Il Elementary Rules of Usage Just reading that outline makes you a better writer Digging deeper has the same effect Take 13 from 1 Form the possessive singular of nouns with 5 Chapter Omit needless words It begins 2 In a series of three or more terms with a single Vigorous writing is concise A sentence should conjunction use a comma after each term except contain no unnecessary words a paragraph no the last unnecessary sentences for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts This requires not that the writer make all his sentences short or that he avoid all detail and treat his subjects only in outline but that every word tell 3 Enclose parenthetic expressions between commas 4 Place a comma before and or but introducing an independent clause 38 november 2007 www linuxjournal com Familiar Seems to me the same principl
170. nd a value system in which the depen dencies that matter most are ones where buyers rely entirely on sellers Free and open source code does not only express the free choices of its authors but it provides practical ways to expand the freedoms of those who use and depend on that code Before read Alan s piece didn t see the connection between proprietary code and a larger paradigm anchored in persuasion The problem with proprietary code in many cases begins with motivation It s not just about making secret bits and driving up sale value by making those bits scarce It s about controlling the customer The persuasion paradigm puts a premium on captive dependent customers Worse it restricts the usefulness of prod ucts to just what works for the seller This usually involves limiting choices for customers What Alan calls the personal decision making paradigm has been supported from Day Zero in the Free and Open Source Development world What we have here submit is a usefulness paradigm one that has had a quiet and transformative influence on all it supports Today that includes Linux the Internet and countless other useful goods all of which support far more economic vitality and growth than we ever enjoyed from the persuasion paradigm With due credit for all it did achieve in its day share that observation with the intent that it will prove useful If it s not we ll patch it discard it or rewrite it If it is any o
171. ndencies get out of hand In short OpenMP is something you use when xautopar complains Given that for C and C OpenMP is expressed through the pragmas it is quite safe to add these hints although making sure that suggested parallel operations don t have concurrency problems is still your responsibility As with any pragma if the compiler doesn t understand it it ll skip over it At the time of this writing the following freely available Linux compilers support OpenMP 2 5 Intel Compilers GCC 4 2 and Sun Studio 12 So how do we use OpenMP to boost the compiler s confidence in the loop on line 35 Simply add the following pragma to line 34 34 pragma omp parallel for 35 for i 2 i lt N i let the testing begin 36 if 7 primei 1 And don t forget to add to the set of command line options cc fast xloopinfo xautopar xopenmp prime c o prime A the end of the day We as prime c line 14 not parallelized loop has multiple exits prime c line 14 not parallelized loop has multiple exits userland software developers have inlined loop prime c line 31 PARALLELIZED and serial version generated no other choice but to embrace the prime c line 35 PARALLELIZED user pragma used parallel view of the world fully Nice We ve got two out of three loops in our application now completely parallelized Let s see how much faster it runs than POSIX threads do is still not a pa
172. ne also is included www sendio com w sendio AE pum 260010 www linuxjournal com november 2007 43 NEW PRODUCTS Trinity s Digital Audio Workstation Here is an audio device that is not brand new but new to me and hopefully to you too Trinity Audio Group s Trinity Digital Audio Workstation This slick all in one device is a portable professional recording studio that allows one to do anything imaginable with linear audio for example sample edit mix play back and so on Trinity does everything your laptop with an audio interface can do only more conveniently and portably Trinity runs on Linux and works with WAV MP3 and Ogg Vorbis files Several core audio apps are included such as Audacity Hydrogen drum machine Ardour and more Built in 802 11g Wi Fi lets you podcast from the field www trinityaudiogroup com IBM s Big Green Linux Initiative Thanktully firms like IBM are starting to look at our serious environ mental problems as challenges rather than barriers IBM s new Big Green Linux initiative seeks to leverage Linux and other technologies to reduce costs and energy consumption by building cooler data centers for itself and its customers Big Green Linux is a subset of IBM s broader yet similar Project Big Green Specifics of Big Green Linux include server consolidation to System x and System p platforms new efficient products such as the Information Server Blade contributions to the
173. ng and audio processing were met Video tools lagged behind because video processing is both more difficult and more prone to patent encumbrance In the last few years things have begun to catch up to the point where it s feasible to create films or cartoons from concept through execution using only Linux tools Elephants Dream one such cartoon was the foundation for a major breakthrough in open source video Financed by presales of a then unseen cartoon Elephants Dream was a strategy for raising money to advance the development of and raise awareness for the open source 3 D suite Blender www blender org In order to accomplish this goal the creators had to develop some thing that never had been available before an open source compositor Compositing is the art of taking multiple image sources whether from 3 D vector graphics photographs video or procedu rals and marrying them together to create a seamless integrated image A good com positing program provides the means to access all the mathematical functions avail able in the image processing universe and a good artist needs to be able to get down into the guts of an image from time to time below the interface and tweak it directly with mathematical functions Because of Linux s continuing adoption in post houses several high end compositing systems such as Shake D2 Nuke and Eyeon Fusion have been available for years now CT Rn E mem 4
174. ngcorner nl images sheets yahtzee 3 pdf In many ways it s five card draw poker with dice so the first section of the score sheet is for sets ones twos threes and so on where your score for each is the sum of that value on the dice The second section is other poker hands including three of a kind four of a kind small straight four of the five dice have sequential values large straight all five are sequential a full house and one or more Yahtzee rolls You can get bonuses for achieving certain levels including a very nice 35 point bonus for attaining at least 63 on the top section but the score sheet itself is straightforward The key to the game then is to figure out how to score a given roll If you roll four ones do you want to score that as your four of a kind or your ones What if they re both filled in already Fortunately we re going to defer to the player for that but that still leaves us with the data question of how to model the different boxes on the score sheet and the interface question of how to prompt the user to select which box to score Let s take a look Modeling the Score Sheet as an Array As with most of these types of data structures we ll use an array to model the score sheet Count the boxes on the score sheet and you ll see 13 boxes total including the special Yahtzee box where you can roll and get credit for more than one so a game typically has 13 rolls but it could have more 32 n
175. nhanced performance and power management capabilities make the AMD Opteron processor a perfect fit for the Rackform nServ A411 from Silicon Mechanics With four native quad core processors it s like a compute cluster in one rack unit When you partner with Silicon Mechanics you get more than a powerful AMD server you get an expert like Tim _ ime MECHANICS Silicon Mechanics and the Silicon Mechanics logo are registered trademarks of Silicon Mechanics Inc AMD the AMD Arrow logo AMD Opteron and combinations thereof are trademarks of Advanced Micro Devices Inc SILICOM M COLUMNS BEACHHEAD as Big Endian machines were prominent in the market place but it has ignored this ever since Intel AMD reached dominance and SPARCs were the poor kids on the block Third Sun needs to decide what it wants to be when it grows up It continues to spend millions of dollars to duplicate a base operating system when it could be addressing cus tomers needs by better supporting the Linux community and recognizing that the real enemy is a certain closed source proprietary operating system from a company that does not allow real competition Sun needs to redefine its strategy and become a solutions company like IBM and HP are doing while not abandoning its line of VARs and resellers that made Sun great Sun needs to learn how to compete on the really equal playing field that compute
176. nlight Next take the pillars element which is a rendered layer from within Blender proper add a procedural glow layer to it and marry the glow and the pillars to the background To do this take an output from the source and run it through a curves pass to cut out all but the brightest highlights Figure 7 pipe the output from the curves node into a blur node where I do a 40 pixel x y tent blur and then direct that into a Screen node where the glow is composited back over the source picture of the pillars This married image is then piped into an AlphaOver node which pastes the pillars and glow over the top of the photo Now we come to the color keying There are a number of ways to do color keying in a node based compositor not least among them is building your own keyer out of basic mathematical functions Although this method is excellent and yields the best results even on DV footage which has some very particular problems with color keying it requires far more ink than I have space for here So for the sake of brevity selected one of Blender s three native keying nodes the channel key to do the job Figure 8 The footage first off needs some prep and prepared the same footage two dif ferent ways one for pulling the matte and the other for color matching first ran the footage through a scaling node to correct for the 16 9 aspect ratio shot in as the rest of my elements are in 4 3 I m
177. nly 699 1U 690GA Athlon64 X2 Dual Core 4GB DDR2 2x160GB HD Dual LAN 45 custom config available 999 1U 690GA Athlon64 X2 Dual Core 8GB DDR2 2x160GB HD Dual GigaLAN 45 10 Servers Up to 64GB RAM ATB HD Bg OEM ODM Service Available 1 799 1045 690 Athlon64 X2 6000 8GB DDR2 2TB 4x500GB HD Dual Gigabit LAN 2 999 1U 2500A16 2 x Opteron 2212 16GB ECC DDR2 1TB 4x250GB HD Dual Gigabit LAN 4 999 1U 2500A16 2 x Opteron 2216 32GB DDR2 2TB 4x500GB HD Dual Gigabit LAN Option 64GB 4TB HD 10 999 1U 8415SS32 4 x Opteron 8212 64GB ECC DDR2 2x73GB SAS HD 3x Gigabit LAN Option 128GB RAM dj Twin Servers 1U 8 Way Quad Opteron 4 999 1U Twin 2 x 2 Dual Core Processors 2 x 8GB ECC DDR2 2 x Dual 250GB HD 2 x Dual Gigabit LAN STB 3xS00GBHD Dual AN High Density Multi Processor Servers 7 999 1U 8415SS 4 x Opteron 8212 Dual Core 32GB ECC DDR2 2x73GB 15K RPM SAS HD 3x Gigabit LAN Linux Appliance starts at 299 Poly 6100Nx Athlon64 X2 512MB RAM Nvidia 6100 Graphics 80G CD ROM 299 Poly 7050A Athlon64 X2 4200 1GB DDR2 Nvidia 7050 Graphics 500G DVD RW 499 Low Cost NAS Storage 2 Starts at 999 999 Netdisk 4000 2 0TB 4x500G 1 499 Netdisk 6000A 3TB 6x500G 2U 2 999 Netdisk 6000B 6TB 6x1000G 2U 1U to SU Quad to Eight Processors Up to 1286 RAM GTB 2U Storage Server 2012SC 2055A 11 999 2U 8425SS 4 x Opteron 8212 64GB ECC DDR2 4T
178. not do this Either of these are signaled by setting the sinfo flags in the sctp_sndrcvinfo structure to the appropriate value A graceful shutdown is signaled by setting the shutdown flag and writing a message with no data sinfo sinfo flags SCTP sSctp s nd amp sinfo The reader then will be sent an sctp shutdown event if it has that event type enabled The code to handle such an event was shown above This can be done only on one to many sockets though For one to one sockets you are limited to using close Getting the Association ID Many of the calls that deal with associations take an association ID as a parameter Whereas in TCP a connection effectively is represented by the pair of source and destination endpoint IP addresses in SCTP the source and destination can both be multihomed so they will be represented by the set of source and the set of destination addresses For one to many sockets the source addresses may be shared by many associations so need the destination addresses to identify an association properly For a single association these destination addresses all belong to a single endpoint computer The SCTP variation on getsockopt that is sctp opt info is used to find an associa tion from an address The reason cannot simply use getsockopt is that need to pass in a socket address and the return value includes the association value This in out semantics is not supported by al
179. o move that application to the other cluster node A sample application script which was used in my RHEL cluster implementation to provide Listing 2 Sample Application Script Script Name CommS sh Script Purpose To provide application start stop status under Cluster Script Author Khurram Shiraz bin sh basedir home kmefic KMEFIC CommunicationServer case 1 in start cd basedir su kmefic c CommunicationServer f Dev CommunicationServer conf EXTEND Stop z ps ef grep Dev CommunicationServer grep v grep weawk print 2 TUE cS then kill 9 z fuser mk home kmefic exit 0 fi restart root CommunicationS sh stop sleep 2 echo Now starting root CommunicationS sh start echo restarted status ps U kmefic grep CommunicationSe 1 dev null then exit 0 elise exit il fi esac high availability to a legacy C based application is shown in Listing 2 Finally you have to add a shared IP address 172 16 2 188 to the service present in your failover domain so that the service should contain three resources two private resources one filesystem and one script and one shared resource which is the service IP address for the cluster The last step is synchronizing the cluster configuration across the cluster nodes The RHEL cluster administration and configuration tool provides a save configuration to cluster option which will appear
180. o extend use and work with those APIs Web development is increasingly a matter of tying together existing functionality from other sites and understanding these APIs can be quite useful It s also important for Web developers to understand the nature of APIs If you want to create the next Facebook or Google you re going to need to create more than a winning product You re going to need an ecosys tem of developers and third party software around your core product One of the best ways to do this is to create and promote APIs letting people use your application as a platform rather than a standalone program By looking around and seeing what others have done we can get a better sense of just what the possibilities are and how we might use them Read Only Protocols In the beginning when Tim Berners Lee invented the Web he imagined it as a read write medium But for most people who used the Web during the first decade it was a read only medium You could view Web sites with your browser fill out forms with your browser and that was about it There was no API for reading Web sites if you wanted to read the content of a site programmatical ly for example in order to create a searchable index of all Web content you needed to create your own spider program as well as teach it to take apart the HTML This changed in the late 1990s when a number of developers most prominently but not exclusively includ ing Dave Winer creat
181. olina Resources The High Availability Linux Project www linux ha org Heartbeat Home Page www linux ha org Heartbeat Getting Started with Heartbeat Version 2 www linux ha org GettingStartedV2 An Introductory Heartbeat Screencast linux ha org Education Newbie InstallHeartbeatScreencast The Linux HA Mailing List lists linux ha org mailman listinfo linux ha www linuxjournal com november 2007 55 Tee rer FL Lu Eu NM HOBBIT OpenVMS Cluster Hardware Linux E Mail Server Blades and SAN Building a Scalable High Avallability E Mail System with Active Directory and More A large scale implementation of a scalable Linux e mail system with Active Directory 56 november 2007 www linuxjournal com In early 2006 Marshall University laid out a plan to migrate HOBBIT Figure 1 an HP OpenVMS cluster handling university wide e mail services Plagued with increasing spam attacks this cluster experienced severe performance degradation Although our employee e mail store was moved to Microsoft Exchange in recent years e mail routing mailing list and student e mail store including IMAP and services were still served by OpenVMS with about 30 000 active users HOBBIT s e mail software PMDF provided a rather limited feature set while charging a high licensing fee A major bottleneck was discovered on its external disk storage system the dated storage technology resulted
182. om a brand new project It is advancing quickly In future Extent and Nature of Circulation Average No Copies Each Issue No Copies of Single Issue During Preceding 12 Months Published Nearest to Filing Date versions more user friendly keying tools and color tools are planned and hopefully there also will be more direct access to the Net press run 57 908 54 182 Paid and or Requsted Circulation translation and garbage matting functions which at the moment 1 Paid Requested Outside County are obtuse and inconvenient Until such tools emerge I highly Mail Subscriptions on Form 3541 20 086 19 537 that ti t Blend kh 2 Paid In County Subscriptions recommen at anyone wanting to use Blender as a workhorse Stated on Form 3541 0 0 compositor invest in a book that teaches how compositing works 3 Sales Through Dealers and Carriers Street Vendors Counter Sales both in theory and practice The best available is The Art and and Other Non USPS Paid Distribution 25 688 24 005 Science of Digital Compositing The Morgan Kaufmann Series in Total Paid and or Requested Circulation 45 774 43 542 Free Distribution Outside the Mail Computer Graphics Outside County as Stated Using Blender for composite work has significant advantages as e 810 780 n County as State well since it s an integrated part of a 3 D content creation suite on Form 3541 0 0 the particle systems fluid systems procedural textures and a
183. on its journal to make sure that any cor ruption is identified as quickly as possi ble With interest from various folks including Andrew Morton it looks like this feature quickly will be adopted into the official tree although ext4 still remains a fairly experimental filesystem LinuxConf Europe 2007 LCE will host a semi formal discussion of con tainers within the kernel Serge E Hallyn recently announced plans to arrange for a conference room includ ing phone lines for anyone who can t be present but still wants to partici pate and a series of half hour presen tations Containers provide a way to cluster processes into specific name spaces that are isolated from the rest of the system and are related to virtualization projects like Xen Michal Piotrowski has announced the Linux Kernel Tester s Guide translated by Rafael J Wysocki at www stardust webpages pl files handbook handbook en 0 3 rc1 pdf It is a long document representing much work it reads like a book and it clearly explains a lot of material that most discussions on the linux kernel mailing list tend to assume for example how to do a binary search with git to identify precisely when a particular bug was introduced into the tree Several projects have changed hands recently Valerie Henson has had to abandon the Tulip driver and now it looks like Kyle McMartin may become the official maintainer Wim Van Sebroeck has submitted a patch to make M
184. once you start the cluster services Hence for the first synchronization it is better to send the cluster configuration file manually to all cluster nodes You easily can use the scp command to synchronize the etc cluster cluster conf file across the cluster nodes home root gt scp etc cluster cluster conf Commsvr2 etc cluster cluster conf Once synchronized you can start cluster services on both cluster nodes You should start and stop RHEL related cluster services in sequence To start service ccsd start service cman start service fenced start service rgmanager start To stop service rgmanager stop service fenced stop service cman stop service ccsd stop If you use GFS startup shutdown of the gfs and clvmd services have to be included in this sequence Additional Considerations In my environment decided not to start cluster services at RHEL boot time and not to shut down these services automatically when shutting down the RHEL box However if your business requires 24 7 service availability you can do this easily by using the chkconfig command Another consideration is logging cluster messages in a different log file By default all cluster messages go into the RHEL log messages file var log messages which makes cluster troubleshooting somewhat difficult in some scenarios For this purpose edited the etc syslog conf file to enable the cluster to log events to a file that is different from the default log fi
185. ontrol with a bit of programming Non Blocking TCP Here s one way to maximize throughput if the bottleneck is your local LAN this might also be the case in certain crowded ADSL deploy ments Simply use multiple TCP connections That way you can 68 november 2007 www linuxjournal com ensure that you get all the attention at the expense of the other nodes in the LAN This is the secret of download accelerators They open multiple TCP connections to FTP and HTTP servers and download a file in pieces and reassemble it at multiple offsets This is not playing nicely though We want to be well behaved citizens which is where non blocking I O comes in The traditional approach of blocking reads and writes on the network is very easy to program but if you are interested in filling the pipe available to you by pumping packets you must use non blocking TCP sockets Listing 1 shows a simple code fragment using non blocking sockets for network read and write Note that you should use fcntl 2 instead of setsockopt 2 for setting the socket file descriptor to non blocking mode Use poll 2 or select 2 to figure out when the socket is ready to read or write select 2 cannot figure out when the socket is ready to write so watch out for this How does non blocking I O provide better throughput The OS schedules the user process differently in the case of blocking and non blocking I O When you block the process sleeps which Scatter gathe
186. ou specify like so IPAddr 192 168 1 9 24 eth0 In the above example the IPAddr resource is told to set up a cluster IP address of 192 168 1 9 with a 24 bit subnet mask 255 255 255 0 and to bind it to ethO You can pass other options as well check the example haresources file that ships with Heartbeat for more information Another common resource is Filesystem This resource is for mounting shared filesystems Here is an example Filesystemi dev etherd 61 0 opt data xTS The arguments to the Filesystem resource in the example above are left to right the device node an ATA over Ethernet drive in this case a mountpoint opt data and the filesystem type xfs For regular init scripts in etc init d simply enter them by name As long as they can be started with start and stopped with stop there is a good chance that they will work Listings 4 and 5 are haresources files for two of the clusters run They are paired with the ha cf files in Listings 2 and 3 respectively The cluster defined in Listings 2 and 4 is very simple and it has only two resources a cluster IP address and the Apache 2 Web server use this for my personal home Web server cluster The servers themselves are nothing special an old PIII tower and a cast off laptop The content on the servers is static HTML and the content is kept in sync with an hourly rsync cron job don t trust either server very much but with Heartbeat have never had a
187. ovember 2007 www linuxjournal com If we initialize the game by filling in all the array values with a known stop value say 1 then the test for whether a given box has been filled in is easy if scoresheet 1 1 then echo 1 Your one s fi The trick is that we also want to pre qualify these options There s no point in prompting players to select their roll as a Yahtzee if they didn t get five of a kind This proves to be a bit tricky so as a first step I m going to tweak the code to order the dice in the array in ascending order after each roll automatically It might be a long trip to accomplish the task but rather than write a sorting routine in the script I m just going to push out the task to the sort function then read the results back in and fit them into the individual slots of the dice array Sound complicated It is rather function sortDice sorted echo dice 1 echo dice 2 echo dice 3 echo dice 4 echo dice 5 sort index 1 for value in sorted do dice index value index index 1 done You can see here that I m using a temp variable called sorted to store the resultant values and that l m using a subshell that s the notation to do the actual work The hardest part of this little function is to figure out how to put the values back into the array once everything s sorted properly and that s accomplished with the for loop Notice tha
188. performance programming In this article focus on certain generic mechanisms that are guaranteed to provide a noticeable improvement Based on this you should be able to make the final touch with the help of the right tools deal mostly with TCP because the kernel does the bandwidth management and flow control for us Of course we no longer have to worry about reliability either If you are interested in performance and high volume traffic you will arrive at TCP anyway What Is Bandwidth Once we answer that question we can ask ourselves another useful question How can we get the best out of the available bandwidth Bandwidth as defined by Wikipedia is the difference between the higher and lower cutoff frequencies of a communication channel Cutoff frequencies are determined by basic laws of physics nothing much we can do there But there is a lot we can do elsewhere According to Claude Shannon the practically achievable bandwidth is determined by the level of noise in the channel the data encoding used and so on Taking a cue from Shannon s idea we should encode our data in such a way that the protocol overhead is minimal and most of the bits are used to carry useful payload data TCP IP packets work in a packet switched environment We have to contend with other nodes on the network There is no concept of dedicated bandwidth in the LAN environment where your product is most likely to reside This is something we can c
189. pre correcting the footage rather than doing it at render time then ran it through a translate node which allowed me to reposition the footage to the left so that we actually can look over the actress shoulder rather than just staring at the back of her head From there send the output into two parallel subtrees keying and color correction Cursi Figure 6 The Background Nodes Tree 90 november 2007 www linuxjournal com Why an Image Sequence Instead of a Video Working with image sequences offers three distinct advantages over working with video First with image sequences it s easier to retouch problems on individual frames without reprocessing an entire clip Second the variety of alpha enabled lossless formats gives the operator a far greater flexibility than do video formats very few of which are lossless or allow embedded alpha channels Third video codecs are frankly a big pain in the neck They vary wildly in support from one program to another however image formats are universal and comparatively open Converting your video to image sequences before piping it through your compositor or motion tracker means that you re going to encounter far fewer problems with moving between various programs in your work flow With Blender there is one further advantage to using image sequences and it has to do with a shortcom ing of the program Blender does not support NTSC drop or nondrop frame enco
190. primary to become the primary again as soon as it comes back Moving on when Heartbeat thinks a node is dead that is just a best guess The dead server may still be up In some cases if the dead server is still partially functional the consequences are disastrous to the other node members Sometimes there s only one way to be sure whether a node is dead and that is to kill it This is where STONITH comes in 54 november 2007 www linuxjournal com Sometimes theres only one way to be sure whether a node is dead and that is to kill it This is where a STONITH comes In STONITH stands for Shoot The Other Node In The Head STONITH devices are commonly some sort of network power control device To see the full list of supported STONITH device types use the stonith L command and use stonith h to see how to configure them Next in the ha cf file you need to list your nodes List each one on its own line like so node deimos node phobos The name you use must match the output of uname n The last entry in my example ha cf files is to turn on logging use logd yes There are many other options that can t be touched on here Check the documentation for details The haresources File The third configuration file is the haresources file Before configuring it you need to do some housecleaning all services that you want Heartbeat to manage must be removed from the system init for all ini
191. r node could leave things here but the shot could use a little extra touch to tie all the layers together To accomplish this created a nice lens flare and brought it in to Blender ran it through a translate node to put it into the right spot and from there into another screen node which lays it over the top of the previous composite To do this the lens flare went into the top image input and the pre vious AlphaOver node went into the bottom image input and messed with the Fac so got the right effect just a hint of extra brightness and anamorphic smear which helps sell the integration of the different layers Figure 9 Now all that remains is to hook up the Composite node which is what Blender draws from for its output This can be found next to the viewer node under output in the add nodes menu which you get to by pressing the spacebar Once the composite node is hooked up to the output go to the renderbuttons window at the bottom of the screen depress the Do Composite button and click Render or if it s an animation Figure 8 The Color Keying Nodes Tree Figure 9 Layers of the Image Including Lens Flare click Anim Figure 10 The result of your hard work appears in the render window from where you can save it using F3 if it s a still Or you can find it on your hard drive in the temp directory or another 92 november 2007 www linuxjournal com LL CT Cara ai Pond directory that
192. r I O time iov O0 iov 1 iov 2 iov 3 m partial write of iov 0 full write 0 mM full write of iov 0 partial iov 1 Figure 1 Possibilities in Non Blocking Write with Scatter Gather 1 0 Listing 1 nonblock c set socket non blocking fentl acesock OsNONBLOCK void poll wait int fd int events int ms struct pollfd 1 memset char amp pollfds 0 sizeof pollfds pollfds 0 fd fd pollfds 0 events events poll polltids 15 1 lt 0 4 perror poll errx l Poll failed readmore cimt sock Ghar buT size t n iol set nds int ret bytes poll_wait sock POLLERR POLLIN bytes 11 sock buf n if 0 bytes perror Connection closed errx 1 Readmore Connection closure NOT REACHED return bytes readall int sock char our size t n 4 leads to a context switch When you use non blocking sockets this problem is avoided Scatter Gather I O The other interesting technique is scatter gather I O or using readv 2 and writev 2 for network and or disk I O Instead of using buffers as the unit of data transfer an array of buffers is used instead Each buffer can be a different length and this size t pos 6 SSize t res while n gt pos res read sock buf pos mnm pos switch int re
193. r products are now proceed ing toward It can do that but only if it is smarter about it Fourth Sun needs to clean up its marketing messages It claims to have been founded as an open source company In reality Sun was one of the companies that took UNIX into a binary distribution model Although it is true that this model was somewhat forced by AT amp T s arcane licensing strategies of the time it was this movement of UNIX companies to restrict the source code distribution that helped motivate Richard Stallman to produce the GNU suite and the University of California Berkeley to complete the first freely distributable Berkeley Software Distribution do not want to imply that Sun has never helped the Open Source community or contributed to its well being Certainly through time there have been stellar examples of individuals at Sun that have contributed more than their share to the community overall But let s put it into the perspective of a company that has had its share of proprietary closed source products and standards wars Sun does have some good products Its work in multicore chips and multicore development tools illustrated in an article this month by Roman Shaposhnik a Sun employee on page 80 is a good example of Sun leveraging off its technologies Sun also has been doing some good work in environmentally sound server systems and solutions Unfortunately there is a big difference between having good people working
194. rective needs to be escaped or enclosed in quotes single double So the command to display the date and time 18 hours 30 minutes ago in Year Month Day Hour Minute Second format would be i showdate h 18 M 30 f Y m d 99H 96M 96S showdate cannot obtain the date and time by specifying a weekly offset and by taking a positive or negative offset from any datum not just the current date and time Even though showdate has been tried and tested rigorously it is not perfect And if anyone encounters a bug or feels that redesigning the algorithm implementing coding shortcuts or efficiently using system resources can improve the program please contact me by e mail at ssahore yahoo com showdate was designed for computing and displaying the date and time in the past or future depending on the command line options specified as an offset from the current date and time The next step would be to augment showdate to specify weeks and the ability to change its datum Sandeep Sahore gt gt Push and Pop dirs The dirs command combined with pushd and popd is very effective for tracking users directory changes Suppose you have to make some changes to the files present in the following directories B home sangeeth soft release2 src B home sangeeth soft release2 src show B home sangeeth soft release2 doc Instead of noting down the directories on paper do the following pushd home sangeeth soft release2 src pushd home
195. repare on my Ubuntu systems first run the following command sudo apt get build dep heartbeat 2 Check the Linux HA Web site for the complete list of depen dencies With the dependencies out of the way download the latest source tarball and untar it Use the ConfigureMe script to compile and install Heartbeat This script makes educated guesses from looking at your environment as to how best to configure and install Heartbeat It also does everything with one command like so sudo ConfigureMe install With any luck you ll walk away for a few minutes and when you return Heartbeat will be compiled and installed on every node in your cluster Configuring Heartbeat Heartbeat has three main configuration files etc ha d authkeys etc ha d ha cf etc ha d haresources The authkeys file must be owned by root and be chmod 600 The actual format of the authkeys file is very simple it s only two lines There is an auth directive with an associated method ID number and there is a line that has the authentication method and the key that go with the ID number of the auth directive There are three supported authentication methods crc md5 and 1 Listing 1 shows an example You can have more than one authentication method ID but this is useful only when you are changing authentication methods or keys Make the key long it will improve security and you don t have to type in the key ever again Listing 1 The etc
196. rint races 1 No race information recorded in experiments Weird Not only did we get the correct result but also the thread analyzer didn t seem to notice anything unusual Is it broken Not really You see what makes concurrent bugs so notoriously difficult to track down is the fact that most of them are intermittent As with most manifestations of a nondeterministic behavior they come and go The trouble with parallel programming is that it makes some sections of your application nondeterministic depending on how applications are run what else runs on the system and whether you use tools such as a conventional debugger Thread analyzer reports only those problems that did actually occur Well if at first you don t succeed collect r on prime 2000000 Creating experiment database tha 2 er Number of prime numbers between 2 and 2000000 114833 er print races tha 2 er Total Races 2 Experiment Race 1 Vaddr Multiple Addresses Access 1 Write main MP doall from line 34 d1B34 main 0x00000172 line 37 in prime c Access 2 Write main MP doall from line 34 d1B34 main 0x00000172 line 37 in prime c Total Traces 1 Race Z2 Vaddr Oxbffff28c Access 1 Write main MP doall from line 34 d1B34 main 0x00000189 line 38 in prime c Access 2 Write main MP doall from line 34 d1B34 main 0x00000189 line 38 in prime c Total Traces 1 Bin
197. rspective Linux due to its flexibility and the number of people working on refining 11 15 significantly more stable and scalable than other platforms Windows for instance is prone to failure at moderately larger node counts and is not consid ered as an option at government and national laboratories Sixth the nature of open source makes Linux the most convenient platform for vendors and users to work with Standards are broadly defined and supported by a worldwide community of programmers rather than the diminishing numbers found at the remaining propri etary vendors As a result there are no shortages of fully developed tools utilities and software modifications that users and vendors can leverage in order to optimize their systems Conclusion The HPC market has made its choice and the choice is the Linux OS due to its superior performance lower costs and its community of open source developers and vendors Windows may have a lot to offer entry level users especially those with more limited resources or goals Likewise UNIX still has a lot to offer for many legacy HPC applications However both Windows and UNIX require more work to be able to deliver the same functionality and compelling price performance value of Linux The HPC market is more open and competitive than it has ever been but it is clear that Linux is still the best choice for today and the foreseeable future m David Morton hrings 17 years experience in sup
198. s case i if errno EINTR errno EAGAIN continue return 0 case 0 EPIPE return pos default pos size t res return pos Writenw int fd char Dbuf size t m size_t pos 0 SSEM while gt pos poll wait fd POLLOUT POLLERR res write fd buf pos n pos switch int res 1 if errno EINTR errno EAGAIN continue return case 0 errno EPIPE return pos default pos size t res return pos is what makes it so interesting You can transfer large chunks of data split between multiple sources destinations from to the network This could be a useful technique depending upon your application Listing 2 shows a code snippet to illustrate its use When you combine scatter gather with non blocking sockets things get a little complex as shown in Figure 1 The code for tackling this hairy issue is shown in Listing 3 www linuxjournal com november 2007 69 INDEPTH A partial write of any buffer can occur or you can get any combi nation of a few full writes and few partial writes Therefore the while loop has to take care of all such possible combinations mmap 2 Disk Network programming is not all about sockets however We still haven t solved the problem of having to use hard disks which mechanical devices and consequently are much slower than main memory and even the n
199. s even within the same cluster Alliant Techsystems ATK is a recent example of how high performance Linux clusters have matured ATK is an advanced weapon and space systems company with many years of experience working with HPC systems In 2006 faced with upgrading its aging proprietary system the launch system s group invested after extensive benchmarking in a high performance Linux cluster finding one tuned and optimized for CFD FEA and visualization codes The decision reflected their under standing that Linux clusters and vendors had matured We had heard several horror stories of organizations that moved to Linux supercomputers only to suffer through installation times that stretched to six or eight months and beyond said Nathan Christensen Engineering Manager at ATK Launch Systems Group For instance one of ATK s other business units experienced eight weeks of waiting and downtime to get a system into production The Launch Systems Group wanted to avoid a similar experience The system arrived application tuned validated and ready for production use said Christensen We were able to move quickly into full production generating our simulations and conducting our analysis within two weeks of delivery The system also accelerated the company s time to results thereby enabling ATK to complete designs faster and conduct more frequent higher fidelity analysis The launch system s group completes runs three to four
200. s It s an extremely complex protocol with a heavy responsibility on the Internet We often forget that TCP is what holds the Internet together without collapse due to congestion IP connects networks together but TCP ensures that routers are not overloaded and that packets do not get lost Consequently the impact of TCP on performance is higher than any other protocol today It is no wonder that top notch researchers have written several papers on the topic The Internet is anything but homogeneous There is every possible physical layer of technology on which TCP IP works today But TCP is not designed for working well through wireless networks Even a high latency satellite link questions some of TCP s assumptions on window size and round trip time measurement And TCP is not without its share of defects The congestion control algorithms such as slow start congestion avoidance fast retransmit fast recovery and so on sometimes fail When this happens it hurts your performance Normally three duplicate ACK packets are sufficient for triggering congestion control mechanisms No matter what you do these mechanisms can drastically decrease performance especially if you have a very high speed network But all else being equal the above techniques are few of the most useful methods for achieving good performance for your applications Gunning for very high performance is not something to be taken lightly It s dependent on heuristics
201. s adding resources to this service added a private resource of the filesystem type which has the characteristic of device dev sd3 mountpoint of shared data and mount type of ext3 also added a private resource of the script type root Comms sh to service CommSvc This script will start my C based application and therefore it has to be present in the root directory on both cluster nodes It is very important to have correct ownership of root and security otherwise you can expect unpredictable behavior during cluster startup and shutdown Application or database startup and shutdown scripts are very important for a RHEL based cluster to function properly RHEL clusters 50 november 2007 www linuxjournal com use the same scripts for providing application database monitoring and high availability so every application script used in a RHEL cluster should have a specific format such scripts should at least have start and stop subsections along with a status subsection When an application or database is available and running the status subsection of the script should return a value of 0 and when an application is not running or available it should return a value of 1 The script also should contain a restart subsection which tries to restart services if the application is found to be dead A RHEL cluster always tries to restart the application on the same node that was the previous owner of the application before trying t
202. s now an independent consultant in Free and Open Source Software FOSS Business and Technical issues inte Leap ahead MAXIMIZE PROCESSING PERFORMANCE AND MAXIMIZE RESPONSIVENESS M TA 2 EY i m E E CRT NI NOR TECH PORTABLE CLUSTER e Lightweight and designed for mobility Y o e Ruggedized chassis Xeon ide ensures safe transit SNOCK e Ultra energy efficient Qua d core Unmatched LEE d P remm 7 Intel the Intel logo Intel Leap ahead the Intel Leap ahead logo Xeon and Xeon Inside are trademarks of Intel Corporation in the U S and other countries Other names and brands may be claimed as the property of others 2007 Intel Corporation All rights reserved Nor Tech the Nor Tech logo Nor Tech HPC Clusters and Nor Tech Portable Clusters are trademarks or registered trademarks of Northern Computer Technologies COLUMNS LINUX FOR SUITS DOC SEARLS The Usefulness Paradigm If you don t like the usefulness paradigm submit a patch don t write code but do write prose It s different but there are similarities and overlaps Code writers have also supplied me with a useful cache of metaphors For example can explain my writing method as a debugging and patching process and not just because those are metaphors for editing Rather it s because regard most of my writing less as finished work than as useful information
203. s pogolinux Pogo Linux Inc 701 Fifth Ave Suite 6850 Seattle WA 98104 AMD Athlon Athlon XP and the AMD logo are registered trademarks of the Advanced Micro Devices or its subsidiaries in the United States and othercountries For additional terms and conditions please visit www pogolinux com COLUMNS cooking WITH LINUX Figure 3 Explosions They never told me there would be explosions can get SuperTuxKart from supertuxkart berlios de Your next step is to choose whether you want to race on your own for practice or enter a race with other players These can be other humans masquerad ing as SuperTuxKart characters of course or they can be computer AI players Once your cast is assembled it s time to select a race type and course You can indulge in a Grand Prix event that takes you through all 13 courses a handful or simply go for a single race and select a time trial Once you are lined up at the starting line don t be too hasty putting the pedal to the metal or you ll be fined penalty points Once you are off your car can do some interesting things besides drive For starters you can momentarily jump above your competition and any obstacles in your path Keep moving and collect spin ning cubes along the way as these contain things like rockets which you then can fire at opponents and obstacles alike Figure 3 Try to pick up the spinning fish coins as well a penguin s gotta eat The courses
204. s to direct IMAP POP3 traffic to multiple back end mail store nodes Although we found other ways to scale out Cyrus IMAP for example Cambridge University s pair wise replication approach mentioned in the Related Solutions section of this article or using a clustered filesystem to share IMAP storage partitions between multiple servers with products like Red Hat s Global File System GFS compared with the aggregation approach these solutions either are too customized to support the Cambridge approach or involve extra cost GFS is sold separately by Red Hat Inc So the Cyrus IMAP Aggregation approach was adopted Figure 4 illustrates the setup two Cyrus back end servers were set up and each handles half the user population Two Postfix MTA front end nodes are designated to serve the proxy functions When e mail clients connect through SMTP IMAP POP3 to the front end servers the Cyrus Proxy service will communicate with 58 november 2007 www linuxjournal com ien i E N i l u AM Kerberos EF s Authentication Krb5 Client amp ub daomain edu i Active Directory Local File Figure 5 Linux Authentication and Authorization Against AD the Cyrus Master node using the MUPDATE protocol so that it gets the information about which Cyrus back end node stores e mail for the current client Furthermore the back end Cyrus nodes will notify the
205. s when necessary at a lower level in the runtime platform The developer cannot specify programs that deadlock or that have race conditions in the same way that a Java developer cannot specify programs that have memory leaks LJ 1 see Hewlett Packard software ran 32 2 times faster after the software was adapted to use RapidMind How long did it take to modify the software to use RapidMind McCool Our collaboration with HP was a great test of our plat www linuxjournal com november 2007 65 INDEPTH form Roughly the same amount of time was taken to RapidMind enable the application as was taken by HP to tune its single core baseline version The tuning by HP sped up its version by a factor of 4 whereas RapidMind running on an NVIDIA 7900 GPU outperformed that by a factor of more than 32 More recently we have run the same code on an NVIDIA 8800 GPU and sped it up by an additional factor of 5 and we also have run the RapidMind version on our multicore CPU quad core product and achieved a speedup of 8 over HP s version So the benefit to the software organization Is quite startling For the same effort you can use RapidMind not only to get significantly higher performance on the same multicore processors you re already targeting but you can leverage the additional performance of accelerators as well The RapidMind version also will scale automatically to future processors with more cores LJ Is the speed increase in
206. settings in the database Automated scripts running on the front end nodes will query the database for user settings and build Postfix maps to apply these settings A Postfix server can be thought of as routers not for IP pack ets but for e mail For each e mail message Postfix looks at the destination envelope recipient and the source envelope sender and then chooses how to route the e mail message closer to its destination Lookup tables called Maps such as Transport Virtual Canonical and Alias Maps are used to find the next hop e mail delivery location or apply e mail address re rewrites A background job is running on each of the front end e mail hub nodes to pull the e mail settings delivery location e mail alias and group alias information stored in the e mail user database to the Postfix maps aliases virtual canonical and transport Written in Perl the program is configured to run periodically as a crond job Our design principle of the new e mail system is to scale out from a single monolithic architecture to multiple nodes sharing the same processing load In a large e mail environment scaling out the front end MTA system is considerably easier compared with scaling out the back end mail store As the front end nodes are essentially data less using DNS or IP based load balancing on multiple front end servers is a typical practice However the same technique cannot be applied to design the back end mail store w
207. st invented the language was so weird nobody else wanted the job His first UNIX exposure was with Slackware 3 0 and he s been hooked ever since Currently he works for Sun Microsystems in the Developer Products Group He is usually found pondering the question of how to make computers faster yet not drive application developers insane He runs a blog at blogs sun com rvs and can be reached via e mail at rvs sun com IP Transit E he net Gigabit Ethernet Run BGP IPv6 IPv4 Colocation Full Cabinet Holds up to 42 1U Servers 4 00 month 5 M bps Full 100 Mbps Port Full Duplex 2 Order Today email sales he net or call 510 580 4190 he net ip transit html INDEPTH High Performance Linux Clusters The present and future of high performance computing DAVID MORTON Twice a year a group of scientists in Europe and the United States release a list of the world s 500 most powerful computing systems The Top 500 list is the most prestigious ranking of its kind with ven dors and users leveraging favorable rankings to promote their work The most recent list released June 2007 reconfirmed a recent trend Linux is by far the most frequently used operating system in high performance computing HPC Consider the numbers 389 machines or 7896 run some flavor of Linux 64 run UNIX two run Windows and 42 feature a mix of Linux and other operating systems Although such domi
208. switch to Solaris With partners like this you really don t need competitors Second Sun has had a long and troubled history with maintaining the consistency it brags about corporate decisions that went in the face of what its customer base really wanted such as The very painful migration of BSD SunOS to System 5 0 based Solaris and the needless renaming and subsequent system administration issues of the BSD based SunOS code base to Solaris 1 x even though it was the same code base B Supporting and then decommitting from Solaris Intel not once but twice m Ignoring the fact that SPARC is big endian and Intel is little endian so that binary data often is incompatible NFS takes care of that says Sun at a tradeshow No it does not says maddog back to them at the same show Endianism was a point that Sun kept pushing as long Expert Included Tim is dedicated to processes that make every server from Silicon Mechanics a model of consistency and reliability The build and quality processes he applies guarantee that your server arrives ready to perform He has been planning and is ready for the industry s first native quad core processor now available from AMD The Quad Core AMD Opteron processor operates within the same power and thermal envelopes as their dual core counterparts so customers who upgrade can expect to benefit from quad core technology without compromising on power consumption E
209. t by a lucky coincidence for loops automat ically step through fields separated by white space spaces and carriage returns so it s perfect for breaking the resul tant sorted sequence back into individual values We re running low on space this month and I m afraid ended up spending quite a bit of time talking rather than coding I ll make it up to you dear reader next month Dave Taylor is a 26 year veteran of UNIX creator of The Elm Mail System and most recently author of both the best selling Wicked Cool Shell Scripts and Teach Yourself Unix in 24 Hours among his 16 technical books His main Weh site is at www intuitive com and he also offers up tech support at AskDaveTaylor com SUPERMICR SHOES NS Chassis Management Module Features Intel Xeon and AMD Opteron DP MP Holds up to 10 14 server blades Six enclosures fit a 42U rack 90 High Efficiency 3 1 redundant power supplies Chassis management modules 4x DDR Infiniband switch Gigabit Ethernet switch modules Gigabit Ethernet pass thru modules InfiniBand switch modules 20 Gb s x2 Application Optimized for Enterprises Financial Services Databases Data Centers Science Labs HPC Personal Super Computer e i a WWW Supermicro com CMM IPMI View AMAX Arrow Electronics ASI Bell Micro Ingram Micro MA LABS Synnex Tech Data 1 800 800 6328 1 888 427 2250 1 800 2000 ASI 1 800 232 9920 1 800 456 8000 1 408 941 0808 1
210. t let s pretend it is a real life application In that case we certainly would benefit from as much automation as possible And if you think about it there s no tool better suited for helping us than a compiler after all it already takes care of understanding the semantics of the code in order to perform optimizations Ideally what we would need is a compiler that talks back to us helping us understand the source code better and make reasonable tweaks based on that information Here s how Sun Studio 12 lets you do that cc g fast prime c o prime er src prime Source loop below has tag L3 354 i 2 1 lt N i let the testing begin Function is prime inlined from source file prime c into the code the following line 1 loops inlined Loop in function is prime line 14 has tag L4 36 Jf Ts prame ts Jd Finally Your compiler actually explains to you in plain human language what transformations it applied to the source code to make it faster fast Not only that but it also identifies and tags all key areas such as loops that you later can navigate and inspect for the parallelization potential Identifying parallelism just got easier But what about expressing parallelism Would it be completely out of the question to delegate some of that to the compiler as well After all we are too lazy to use POSIX threads besides they are like the GOTOs of parallel programming anyway The good news is t
211. t although Windows provides some advantages to entry level HPC users high performance Linux clusters have matured Today s Linux clusters deliver better performance at a more attractive price than ever before Clusters are increasingly being demanded as turnkey systems allowing faster time to production and fewer management headaches In addition the very nature of open source has contributed to the strength of high performance Linux clustering Linux clusters adapt more quickly to new technology changes are easier to modify and optimize and benefit from a worldwide community of developers interested in tweaking and optimizing code The Advantages of Linux Based HPC The most important factor in HPC is of course performance National laboratories and universities want ever more powerful machines to solve larger problems with greater fidelity Aerospace and automotive engineering companies want better performing systems in order to grow from running component level jobs such as analyzing the stress on an engine block to conducting more complex multi parameter studies Product designers in a variety of other fields want to graduate from running CAE applications on their relatively slow workstations in order to accelerate the overall design process Performance therefore cannot be separated from high performance computing and in this area Linux clusters excel There are two primary reasons for this maturity and community Maturity With ye
212. t levels On Debian style distributions the command is usr sbin update rc d f service name remove Check your distribution s documentation for how to do the same on your nodes Now you can put the services into the haresources file As with the other two configuration files for Heartbeat this one probably won t be very large Similar to the authkeys file the haresources file must be exactly the same on every node And like the ha cf file position is very important in this file When control is transferred to a node the resources listed in the haresources file are started left to right and when control is transfered to a different node the resources are stopped right to left Here s the basic format lt node resource I resource 2 gt resource 3 gt The node name is the node you want to be the primary on initial startup of the cluster and if you turned on auto failback this server always will become the primary node whenever it is up The node name must match the name of one of the nodes listed in the ha cf file Resources are scripts located either in etc ha d resource d or etc init d and if you want to create your own resource scripts they should conform to LSB style init scripts like those found in etc init d Some of the scripts in the resource d folder can take arguments which you can pass using a on the resource line For example the IPAddr script sets the cluster IP address which y
213. te The pro cess is also silly Not long after Google s Orkut social network site went up Rael Dornfest made fun of the friendship declaring protocol by walking up to people he knew and saying You are my friend Yes or no The second idea is to make society itself a platform Or in Brad s terms to make the social graph a community asset and to build the guts that allow a thousand new social applications to bloom Significantly most social network sites all but MySpace I believe run on Linux Wikipedia too If Brad s right we can equip the rising social network tide that lifts all boats There should even be plenty of work converting today s silos into tomorrow s arks For more visit bradfitz com social graph problem or just look up social graph on the vast Linux hack called Google The lucky top result probably will be Brad s DOC SEARLS Bring SMS to the Live Web with a FoxBox Acme s SMS FoxBox The forces at Acme Systems and KDev two veteran embedded Linux system and software developers based in Italy have conspired to bring the world SMS FoxBox It s a Linux based box dedicated to sending and receiving SMS messages that can be managed through a Web interface It can handle up to 30 incom ing messages at a time on a common SIM card It also works as an SMS to TCP IP gateway so you can combine SMS messaging with network and user applications You can SMS to and from e mail M
214. that is always subject to improvement I m not just here to express I m here to help Okay sometimes just joke around but that s different My model is the most useful tome ever read The Elements of Style by William Strunk Jr and E B White Better known just as Strunk and White the book s 1 0 version en wikisource org wiki The Elements of Style was written in 1918 by Strunk alone when he was a professor of English at Cornell University It was privately published and only 43 pages long It began This book is intended for use in English courses in which the practice of composition is combined with the study of literature It aims to give in brief space the principal requirements of plain English style It aims to lighten the task of instructor and student by concentrating attention in Chapters Il and III on a few essentials the rules of usage and principles of composition most commonly violated The numbers of the sections may be used as refer ences in correcting manuscripts The book is a model of brevity and pith The para graph above is first of the five that make up Chapter which fits on a single page Here is Strunk s outline for Chapters and Ill 5 Do not join independent clauses by a comma 6 Do not break sentences in two 7 A participial phrase at the beginning of a sentence must refer to the grammatical subject 8 Divide words at line ends in accordance with their formation and pronu
215. ties now include devel oping Business Intelligence applications and working on data mining projects at Marshall Resources Migration of Alcator C Mod Computer Infrastructure to Linux by T W Fredian M Greenwald and J A Stillerman www psfc mit edu g papers fed04 pdf HEC Montr al Deployment of a Large Scale Mail Installation by Ludovic Marcotte www linuxjournal com article 9323 Cyrus IMAP Aggregation cyrusimap web cmu edu ag html Scaling up Cambridge University s E Mail Service by David Carter and Tony Finch www uxsup csx cam ac uk fanf2 hermes doc talks 2004 02 ukuug paper html Cyrus IMAP Configuration cyrusimap web cmu edu configuration html Columbia s Cyrus IMAP Move www columbia edu cu news 05 12 cyrus html Indiana s Cyrus IMAP Information uitspress iu edu 040505 cyrus html Stanford s E Mail System Discussion www stanford edu dept its vision email html Windows Security and Directory Services for UNIX Guide www microsoft com downloads details aspx familyid 144f 7b82 65cf 4105 b60c 44515299797d amp displaylang en Toward an Automated Vulnerability Comparison of Open Source IMAP Servers by Chaos Golubitsky www usenix org events lisa05 tech golubitsky golubitsky pdf www linuxjournal com november 2007 59 L i caper Colt qon a ISTE zi ISTE sd a cL 1 I A 2d E 1 gt D Es T NT
216. times faster than before In addition on some of its key CFD and FEA applications ATK has been able to achieve ten times the throughput performance Community The greater Linux community is also an important factor in assuring that Linux based systems deliver the greatest performance The benefit of being open source means that users and vendors from around the world continue to develop innovations and share them with the greater community This enables Linux based HPC systems to adapt more quickly to new hardware and software technologies As a result the ability to take advantage of new processors interconnects and applications is much greater than with proprietary systems Additional Benefits High performance Linux clusters offer a range of benefits beyond raw application performance First Linux is well known for its ability to interoperate with all types of architectures and networks Because of the investment in HPC systems users want to make certain that their systems are as future proof as possible Linux provides users with an operating system that is flexible enough to accommodate virtually any future advancement This is further amplified of course when the larger Linux community working together to solve common problems is again taken into question In addition a variety of tools such as Samba allow Linux to share file services with Windows systems and vice versa Second Linux clusters evolved without headless operat
217. tion algorithms that are more efficient for use on multiple cores The fact that Intel used a non Sun JVM makes this whole question of the future of Java on multicore CPUs interesting won t discount the possibility that Intel may have tuned its code to work best with the BEA JVM But it is a significant plus for Java that you can choose a JVM best suited for the hardware you have The big plus is that you still have to learn only one language Java and this does not limit your choice of architecture or platforms If you run your application on a multicore platform you can choose between JVMs and JVM specific tuning parameters to squeeze extra perfor mance out of your application Now think a bit further into the future Imagine parallelism showing up in a future generation of cell phones or other small devices What better language than a platform neutral one to take advantage of this future Some disclaimers are in order though First don t think any tool or language will soon make optimal programming for multi ple cores or CPUs totally transparent Java has the potential to exploit multiple cores with less impact to the programmer than many other languages however which is why I think Java s future is getting even more promising with this new hardware trend Second although I think Java has the edge other managed multithreaded languages will no doubt ride this same wave Python Ruby and your other favorite language i
218. tive Directory p 56 Cyrus IMAP to the rescue e Distribute Compiles wi distcc p 60 Jack Chongjie Xue 2 november 2007 www linuxjournal com Moe their in _ Write or call 1 J With Coyote Point you ll never have to wonder if your network is fast enough or flexible enough You ll know it is E From local to global load balancing application f acceleration or network manageability Coyote Point leads tl ck We take the Sa A difficulty out of applic i traffic anything faster E na uu 4 out why more than 2 000 on us to astructure Learn what Ci _ A r Web ang oue wah x could mean NOVEMBER 2007 Issue 163 CONTENT COLUMNS INDEPTH 64 PICKING THE RAPIDMINE How to get those cores pumging 22 REUVEN M LERNER S AT THE FORGE Thinking about APIs Nicholas Petreley MARCEL GAGN S COOKING WITH LINUX Because Nothing Says High HIGH PERFORMANCE NETWORKING PROGRAMMING IN C Make the most of your bandWi Girish Venkatachalam MULTIPLE 55 WITH STREAM CONTRO TRANSMISSION PROTOCOL Chat up SCTP Jan Newmarch 5 LAW AND FAST PROCESSING WIT MULTIPLE CPU CORES 32 DAVE TAYLOR S Life in the fast lane WORK THE SHELL Roman Shaposhnik Keeping Score in Yahtzee N
219. tp_sndrcvinfo field of sctp_send So a server simply needs to read a message from any client set the SCTP SENDALL bit and write it back out The SCTP stack then will send it to all live peers There are only a few lines of code nread sctp recvmsg sockfd buf SIZE struct sockaddr amp client addr amp len amp sinfo amp flags bzero amp sinfo sizeof sinfo sinfo sinfo_flags SCTP_SENDALL sctp_send sockfd buf nread amp sinfo The SCTP SENDALL flag has been introduced only recently into SCTP and is not in current kernels up to 2 6 21 1 but it should make it into the 2 6 22 kernels The full code for client and server is shown in Listings 1 chat client c and 2 chat server c SCTP normally delivers messages within a stream in the order in which they were written If you don t need this you can turn off the order ing feature This can make delivery of messages faster as they don t have to be reassembled into the correct order have examined in these three articles how TCP applications can be moved to SCTP and discussed the new features of SCTP So why isn t everyone using SCTP now Well there is the inertia of moving people off the TCP applications onto the SCTP versions and that will happen only when peo ple become fed up with the TCP versions and that may never happen The place to look for SCTP is in new applications using new proto cols designed to take advantage of SCTP 557 Signal
220. u also can use tools like Intel s VTune or even time 1 but whatever you do make sure that performance regression testing is as much a part of your testing routine as the regular regression testing is You do regression testing don t you Identifying parallelism in an existing application usually starts with finding spots with data parallel characteristics task parallel characteristics and figuring out a scheduling model to tie the two together Data parallelism usually can be found in applications working with large sets of global or static data think audio video and image processing gaming engines and rendering software Task parallelism on the other hand mostly is appropriate when branch and bound computation takes place think Chess solvers when a bunch of tasks are asked to do similar calculations but if one finds a solution there s no need to wait for others Once you ve identified all potential sources of the parallelism in your application you have to decide what programming tech niques to use for expressing it For an application written in C or C the most commonly used one happens to be explicit paral lelization with POSIX threads This method has been around for decades and most developers usually have some familiarity with it On the other hand given its inherent complexity and the fact that it no longer is the only game in town I m going to skip over it Let s look at this sample code which happens to be a v
221. un either customized profiles or predefined ones that automate industry standard best practices from the National Institute of Standards and the Center for Internet Security Security Blanket supports Red Hat Enterprise Linux 4 and 5 www trustedcs com Please send information about releases of Linux related products to James Gray at newproducts linuxjournal com or New Products c o Linux Journal 1752 NW Market Street 200 Seattle WA 98107 Submissions are edited for length and content 44 november 2007 www linuxjournal com RouterBOARD 333 www mikrotik com Triple Shot AP Firewall Routing 180 PowerPC E300 266 333MHz CPU QUICC Engine 175MHz Coprocessor Up to 81 000pps Full duplex 3xFE throughput 64MB DDR RAM Onboard NAND storage Three 10 100 ethernet pons MDI X EE jw TT fem ala 4 r m rote S r NITE LERE Y t f X ti ore i jn PLIN P gt SL E v tcm m pme TRIPLE SHOT i 11 MH HE 1 TELE ERE LEER EE E routarbaard ceam 9 gt F e aq ra ec E i es lai n a ad RH E Enterprise Linux Cluster Suit
222. unstudio downloads express index jsp FFMPEG ffmpeg mplayerhq hu Intel VTune www intel com cd software products asmo na eng 239145 htm Intel Thread Checker www intel com cd software products asmo na eng 291669 htm TotalView Debugger www totalviewtech com index htm POSIX Threads www mhpcc edu training workshop2 pthreads MAIN html OpenMP www openmp org Effective Use of OpenMP in Games https www cmpevents com Sessions GD EffectiveUse ppt Intel Thread Building Blocks osstbb intel com Cilk supertech csail mit edu cilk The Problem with Threads www eecs berkeley edu Pubs TechRpts 2006 EECS 2006 1 pdf The Free Lunch Is Over A Fundamental Turn Toward Concurrency in Software gotw ca publications concurrency ddj htm include algorithm include lt iostream gt void standard input sorter using namespace std vector lt string gt v copy istream iterator string cin istream_iterator lt string gt back inserter v sort v begin v end CC c fast xloopinfo xautopar xopenmp library stlport4 sorter cc The above produces a pretty long list of complaints explaining why a particular section of the STLport library cannot be parallelized The key issue here is that certain areas of are notoriously difficult to paral lelize by default Even with OpenMP things like concurrent container access are much more trouble than they are worth Do we have to rewrite STL Well seems like Int
223. ve the Sun people who service or resell those servers approach my customers and tell them that my solution is bad particularly when that story is based on half baked marketing messages with no staying power When was at DEC was making fairly good money in a fairly stable job with good benefits saw no issue in sell ing both Digital UNIX and Linux on the Alpha What my customers asked for sold them When customers asked my opinion gave them the best answer could for their solu tion At that time Digital UNIX was a commercially robust and feature full implementation and Linux lacked in a lot of the features that Digital UNIX offered did not tell cus tomers to buy Linux or buy Digital UNIX because they both made money for Digital could however see the writing on the wall knew that over time Linux would have all the features of a fully robust commercial system that it would be used as the research arm for computer science and that companies pouring 200 300 million a year into developing their own version of UNIX would not be able to compete with an operating system and kernel being developed jointly by many companies and many minds left that stable job at DEC because I believed in the Linux community and the free software model and because I did not want to embarrass DEC by actively and aggressively criticizing its biggest business partner Microsoft Now Sun runs the risk of alienating what could be its big
224. ve to assign IP addresses to ILO devices with the name of the ILO device assigned 172 16 1 100 with Commilo1 as the name of ILO device on 1 and 172 16 1 101 with Commilo2 as the ILO device name on node2 Be sure however to connect Ethernet cables to the ILO adapters which usually are marked clearly on the back side of HP servers Once rebooted you can use the browsers on your Linux servers to access ILO devices The default user name is Administrator with a password that usually is available on the hard copy tag associated with the HP servers Later you can change the Administrator password to a password of your choice using the same Web based ILO administration interface Setup of the Shared Storage Drive and Quorum Partitions In my cluster setup environment used an HP fiber based shared storage MSA1000 I configured a RAID 1 of 73 5GB using the HP smart array utility and then assigned it to both of my cluster nodes using the selective host presentation feature After rebooting both nodes used HP fiber utilities such as hp scan so that both servers should be able to see this array physically To verify the physical availability of shared storage for both cluster nodes look in the dev proc proc file for an entry like dev sda or dev sdb depending upon your environment Once you find your shared storage on the OS level partition it according to your cluster storage requirements used the parted tool on one of
225. vided more details around its plan to make Linux the most supportive envi ronment for mobile device and application development Chief among these is the Hiker Application framework that fills in some of the formerly missing APIs for mobile applica tions Hiker originally was available through the MPL Mozilla Public License but it reportedly will be dual licensed with the LGPL v2 license as well Looking beyond the superficial resem blances between what ACCESS showed and the now familiar iPhone it s clear that the mobile application market will divide between Web based iPhone and native OS based ACCESS OpenMoko maemo with the latter embracing legacy apps developed for other platforms as well Thus the pavement gets wider on the road to truly open mobile devices and markets that grow on them DOC SEARLS Raising the Social Tide Brad Fitzpatrick has a long pedigree for a young guy Besides creating LiveJournal one of the earliest and most popular blogging services and an open source one at that he is the creator of OpenID Perlbal MogileFS memcached djabberd and many other fine hacks Astute readers may recall Distributed Caching with Memcached which Brad wrote for Linux Journal in 2004 Today memcached is one of the world s most widely used distributed caching methods while OpenID is a breakaway leader in the user centric identity field In August 2007 Brad published Thoughts on the Social
226. wdate y 5 m 2 d 23 f Y m d The options can appear in any order as long as their contextual usage is unambiguous therefore the command line above could be written as showdate m 2 f Y m d d 23 y 5 The offsets can be combined in a single command line howev er mixing them up can lead to unexpected and erroneous results If now is January 1st 2003 12 00 00 AM UTC showdate outputs showdate m 8 M 32 Wed May 1 00 32 00 2002 The above command displays the date and time in the past eight months ago but 32 minutes from now while the one below displays the date and time in the future 8 months from now but 32 minutes ago showdate m 8 m 32 Sun Aug 31 23 28 00 2003 The capabilities of showdate can leveraged to specify sub minute job scheduling times A quick way to schedule a batch job 12 minutes and 35 seconds from now would be 4 showdate M 12 s 35 f Y m d H M S xargs at f job file t The current date and time is tracked as the number of seconds that have elapsed since the epoch This number is stored in a signed long which means that on a 32 bit system the timekeeping will break on Tuesday January 19 2038 at 03 14 08 UTC when the value over flows and becomes negative An error is returned if the desired date and time exceeds this limit as shown here showdate y 1000 showdate required time exceeds system limit The presence of whitespace characters in the formatting di
227. wreck of the HMS Association and several other ships from the British fleet off the Isles of Scilly on October 22 1707 1 400 British sailors died continued This accident led John Harrison a carpen ter to develop the marine chronometer a clock accurate enough to calculate longitude easily while at sea Harrison s life is a fascinating story of perseverance and hard work which led to many important inventions including bi metal strips and the roller bearing Unfortunately England s Board of Longitude kept rejecting the work done by Harrison citing inaccuracies in the running of the clocks and it was felt that part of this rejection was because Harrison was a humble carpenter and not a gentleman Eventually the king had to intervene to see that justice was done Aboard the Agape e mail is my prime method of commu nication and lately have been receiving messages from Sun Microsystems telling me should be switching from Linux to Solaris They cite many reasons for doing this and although some are features of Solaris that have not yet been incorporat ed into Linux most of them reek of marketing hype The first message received May 25 2007 told me that Solaris offers one thing Linux does and 600 things it does not The Solaris OS is free and open source same as Linux Yet nowhere in the rest of the message does Sun identify those 600 things that Solaris offers Nor could find them listed on Sun s Web site wh
228. y important that distccd processes are not run as root but are run as the distcc or nobody user 15 also extremely important to think carefully about your allow statements and ensure that they are locked down appropriately for your network In an environment such as a home or small workplace network where you re security firewalled off from the outside world and people can be made accountable for not being good neighbours on the network distcc is secure enough It s extremely unlikely that anyone could or would exploit your distccd hosts if they re not running the daemon as root and your allow statements limit the connecting machines appropriately There is also the issue that those on the network can see your distcc traffic source code and object files on the wire for anyone to reach out and examine Again on a trusted network this is unlikely to be a problem but there are situations in which you would not want this to happen or could not allow this to happen depending on what code you are compiling and under what terms On a more hostile network such as a large university campus or a workplace where you know there is a problem with security these could become serious issues For these situations distcc can be run over SSH This ensures both authentication and signing on each end and it also ensures that the code is encrypted in transit SSH is typically around 2596 slower due to SSH encryption overhead The configuration is very sim
229. ySQL Web scripts desktop widgets whatever SMS FoxBox is ideal for use in Live Web conditions Broadcasters can use it to interact with their audiences Emergency services can use it to flow live reports onto Web sites or broad casts Lightweight monitoring alarm sending trouble ticketing and remote device management can be moved to SMS from other methods Databases and address books can be kept current The unit comes with a GSM quad band modem an SD MMC card for storing messages it comes default with 512 It runs on the 2 6 Linux kernel has a BIS module for failover to up to two backup appliances and an internal clock with a backup battery and NTP support By the way you might remember Acme as the source not only of the tiny Acme Fox embedded Linux system board but for its optional Tux Case as well Today that also can come with an Acme Fox SBC single board computer With Kdev s FoxServe firmware it can work as a dynamic Web server Apache PHP SQLite SSL TLS and so on Tux Case Showing Separate Parts Resources Acme Systems www acmesystems it KDev www kdev it joomla Company Visuals www kdev it HTDOCS press html bOC SEARLS USER FRIENDLY by J D Frazer LINT THE INCLUSION OF A LINUX PC IN EVERY SEAT ON SINGAPORE AIRLINES NEW A380 WILL EVENTUALLY CAUSE A MICROSOFT VP ON A FLIGHT TO LOSE HIS COOL ENOUGH
230. you have set for output in the renderbuttons window Simple though this project is it gives a good grounding in how nodes work and why they re useful Enough access to basic Do you take the computer doesn tdo that as a personal challenge So do we JOURNAL Since 1994 The Original Monthly Magazine of the Linux Community Subscribe today at www linuxjournal com INDEPTH Game framing sed inna Backbuf Edge Edge ings Free Tex Image Figure 10 Click Render or Anim in the Blender Controls production to Elephants Dream gives us more such innovations that push the compositing system to the next plateau Until then there is much to explore learn and use Open source compositing has finally arrived Enjoy m Dan Sawyer is the founder of ArtisticWhispers Productions www artisticwhispers com a small audio video studio in the San Francisco Bay Area He has been an enthusiastic advocate for free and open source software since the late 1990s when he founded the Blenderwars filmmaking community www blenderwars com Current projects include the independent SF feature Hunting Kestral and The Sophia Project a fine art photography book centering on strong women in myth Statement of Ownership Management and Circulation Publication Title Linux Journal PO Box 980985 10 Owner s Publication Number Houston TX 77098 Carlie Fairchild 1075 3583 9 Full Names and Compl
231. your Web based application either using your Web site or alternatively the command line or their own home grown application Facebook Facebook the social networking site started by Mark Zuckerberg has become an extremely popular application on the Web Facebook users can connect with friends join groups of like minded individuals and send messages to others Early in 2007 Facebook became popular among developers as well as users for creating a developer API that goes far beyond the APIs have described above In a nutshell Facebook invited developers to create and deploy new applications that are seamlessly integrated into the full Facebook experience Facebook isn t the only site that lets you incorporate your own code into the site However the style and methods of this integration are deeper on Facebook than have seen elsewhere In the Facebook model your Web application still resides on your server but its output is displayed inside the user s Facebook page alongside other Facebook applications This definitely is something new and exciting can t think of any other Web sites that make it possible for an independent developer to distribute code that integrates into the Web site The fact that you can use whatever language and platform you prefer communicating with Facebook in a certain way marks the beginning of a new kind of API one in which users can affect the Web service as seen by all users not just one particular

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