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Sun StorEdge Network Data Replicator 3.0 System Administrator`s

1. Displaying a List of Current Volume Sets and Group Names on page 42 Getting Sun SNDR Software and Storage Cache Statistics The semadm Command on page 51 Chapter 1 Overview 11 12 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 CHAPTER 2 Configuration Files and Bitmaps This chapter describes specifying a Sun SNDR software Version 3 0 configuration file and converting configuration files from the Sun SNDR software Version 2 0 It also describes bitmap considerations and how to create bitmaps The topics in this chapter include m Using a Configuration File on page 14 m Configuration Files from Version 2 0 on page 15 m Bitmaps on page 16 m Using More Than 64 Sun SNDR Software Volume Sets on page 17 Using a Configuration File When you enable the Sun SNDR software using the usr opt SUNWesm sbin sndradm command you can specify an optional configuration file containing information about the volume set volumes primary and secondary hosts bitmaps Sun SNDR operating mode and so on You can also enter this information from the command line The fields for the configuration file specified using the f config file option are similar to those in the SNDR set described in Command Option and Parameter Summary on page 20 phost pdev pbitmap shost sdev sbitmap ip synclasync g io groupname C tag See TABLE 2 1 See the rdc cf man page for m
2. If the primary volume is RAID 5 protected its contents are striped across several physical disks The local system considers the primary volume inaccessible and yields to the Sun SNDR software remote volume access only when two or more of the disks in the RAID 5 stripe fail 78 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Data Flow FIGURE 4 5 shows the Sun SNDR software transparent pass through of read requests to the remote system bypassing the local disk failure Writes continue to be handled as with a working local disk though no destaging occurs on the primary system 1 Host A issues a read request R for failed local disk on host1 2 If the disk block is resident in host 1 cache it is immediately returned However if the read results in a cache miss the attempt to access the local disk fails and the Sun SNDR software forwards the read request to host2 3 The Sun SNDR software on host2 acts on the remote request by reading its remote mirror disk 4 The Sun SNDR software on host 2 responds to host1 with the requested disk blocks The read data is used to refresh host1 cache 5 The read data is returned to Host A from host1 cache Site A Primary Remote Site B Secondary Disk Disk Cache HBA HBA Cache 1 gt R iii iii gt NI 5 lt of 3 a Host A zi iul i E
3. Overview Caution Do not install or use the Sun StorEdge Version 3 0 Core and data services software on servers in a Sun Cluster 3 0 environment The Version 3 0 software is not co existent with the Sun Cluster 3 0 environment The Version 3 0 software is co existent in the Sun Cluster 2 2 environment where it will not interfere with failover The Version 3 0 core and data services software is cluster aware in the Sun Cluster 3 0 Update 1 environment and provides high availability for the Sun StorEdge software This chapter describes the Sun StorEdge Network Data Replicator Sun SNDR software and its capabilities The topics in this chapter include Sun SNDR Software Description on page 2 Sun StorEdge Instant Image Software on page 9 Network Protocols on page 9 What Happens When Volume Sets Do Not Match on page 10 Getting Started Task Summary on page 11 Sun SNDR Software Description The Sun SNDR software is a remote replication facility for the Solaris operating environment It is intended for use as part of a disaster recovery and business continuance plan to provide redundant storage of critical information across physically separate sites The Sun SNDR software enables you to replicate disk volumes between physically separate primary and secondary hosts in real time To transport data the Sun SNDR software uses any Sun network adapter that supports TCP IP A Sun SNDR software v
4. Pi Local 2R Remote 4y 12 disk ii image disk lt lt 4R Host B Indicates intersite fiber FIGURE 4 5 Pass Through Reads to Bypass Local Disk Failure Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 79 AN v Example To Restore a Failed Primary Volume Caution Disabling the Sun SNDR software on the failed device causes application access to the device to fail and disassociates the failed primary volume from its secondary copy Keep the failed volume enabled under Sun SNDR software control The Sun SNDR software marks the device as failed when it is unable to read or write from it The Sun SNDR software continues to provide read and write services to the host application using the secondary volume at the remote site The remote volume can be used to satisfy I O requests only while in replicating mode As soon as logging mode is entered the I O fails To determine if the problem is a hardware failure requiring part replacement or a transient error an experienced system administrator should carefully examine the var adm messages file If it is a hardware problem contact Sun Enterprise Services to arrange for replacement of the failed device and restoration of the associated logical volumes Quiesce the application using the failed primary volume If autosynchronization is off and you have installed Sun StorEdge Instant Image perform any Instant Image opera
5. Perform this operation on both hosts if you are deleting a volume set When enabling the Sun SNDR software for the first time issue the command from both hosts Ensure that both hosts are enabled Ensure that both hosts are enabled Perform on primary only if a synchronization is in progress Perform on the secondary host if the primary host failed Perform on either host if no synchronization is in progress Chapter 3 Sun SNDR Software Commands 27 Enabling the Sun SNDR Software Note When you first enable the SNDR software you must enable it on the primary and secondary hosts Use the commands to enable the SNDR volume set and start scoreboard logging Also use these commands to create one to many and multihop sets See One to Many and Multihop Volume Sets on page 6 When you enable the Sun SNDR software using sndradm e or sndradm E the SNDR software is enabled for the specified SNDR set and optional I O group These commands also enable you to add volume sets to I O groups when you specify the g io groupname as part of the SNDR set options Using a Volume Set Name When you first enable a set the Sun SNDR software assigns a default volume set name of shost sdev where shost is the secondary host name and sdev is the secondary volume partition name separated by a colon The volume set name is referred to in this document as set name After executing these commands you can use th
6. sndradm a onloff g io groupname C tag n config file SNDR set set name Chapter 3 Sun SNDR Software Commands 49 Setting the Asynchronous Queue Use the following commands to set the maximum number of writes or 512 Kbyte blocks that can be queued in asynchronous mode sndradm W This command enables you to set the maximum number of write operations queued to an asynchronous mode volume set The default value number is 60 For example set this value to 1 to ensure that the secondary volume is never more than one write operation behind the primary volume Syntax sndradm W value g io groupname C tag n config file SNDR set set name sndradm F This command enables you to set the maximum number of 512 Kbyte blocks in the asynchronous queue The default number is 800 Syntax sndradm F value g io groupname C tag n config file SNDR set set name 50 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 scmadm Getting Sun SNDR Software and Storage Cache Statistics The scmadm Command This command displays storage cache information and can be used to view Sun SNDR software statistics Refer to the scmadm man page for more information about this command So After you type usr opt SUNWscm sbin scmadm S with the desired options you can use the keys described in TABLE 3 5 TABLE 3 5 Keys Used in scmadm Display Press This K
7. Mutual Backup Considerations At times the distinction between primary and secondary sites can become blurred As applications are geographically distributed a storage system at Site B can function as a remote volume backup to Site A and as a direct storage resource for applications on Host B Under these circumstances keep replicated volume copies of Host B volumes at Site A This reciprocal backup arrangement supported by the Sun SNDR software is known as mutual backup With mutual backup the Sun SNDR software volumes considered primary by Site B are administered from the Site B session Site B replicated volume devices are considered secondary volumes at Site A 62 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Using the Sun SNDR Software With Sun StorEdge Instant Image Software The Sun StorEdge Instant Image software is an optional software component You can combine the Sun SNDR software with volumes from Instant Image software to create multiple copies of each device See Adding and Deleting Instant Image Software Volumes on page 32 The Instant Image software is a point in time volume copy data service for the Solaris operating environment With Instant Image software you create a volume pair a point in time logical volume copy shadow from the original logical volume master which you specify Once the shadow is established you can read from and write to this shadow volume and the mast
8. Note If a synchronization initiated by the sndradm mor sndradm m r commands is interrupted use the sndradm u update command to complete the synchronization Use usr opt SUNWscm sbin scmadm S to view the synchronization progress Use the sndradm m command when all of the following cases exist m The contents of the primary and secondary volumes may be inconsistent No scoreboard logging information exists to incrementally resynchronize the volumes m The primary volume has the desired contents m You wish to completely overwrite the contents of the secondary volume Use the sndradm m r command when all of the following cases exist m The contents of the primary and secondary volumes may be inconsistent m No scoreboard logging information exists to incrementally resynchronize the volumes m The secondary volume has the desired contents m You wish to completely overwrite the contents of the primary volume sndradm m This command enables you to start a full copy operation from the primary volume to the secondary volume It also enables replication concurrently from the primary volume to the secondary volume any new writes to the primary volume are also replicated to the secondary volume Syntax sndradm m g io groupname C tag n config file SNDR set set name 34 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 sndradm m r This command enables you to start a
9. a primary volume is first explicitly copied to a designated secondary volume to establish matching contents As applications write to the primary volume the Sun SNDR software replicates changes to the secondary volume keeping the two images consistent In synchronous mode a write operation is not confirmed as complete until the remote volume has been updated In asynchronous mode a write operation is confirmed as complete before the remote volume has been updated 2 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Features TABLE 1 1 describes the Sun SNDR software features TABLE 1 1 Sun SNDR Software Features This Feature Enables You To Active logging Backward compatible rdcadm command Disaster rehearsal rollback Granularly configurable Groups of Sun SNDR volume sets Multihop sets Mutual backup One to many sets Continue scoreboard logging operations whenever the Sun SNDR software is disabled or interrupted Maintain the integrity of scripts you have written and want to continue using The Version 3 0 sndradm command is linked to the rdcadm command and is generally compatible with Sun SNDR software Version 2 0 rdcadm command See TABLE 3 1 on page 21 Simulate a disaster without committing data changes to volumes Configure the Sun SNDR software to operate on a logical volume you can exclude volumes containing noncritical data from the Sun SNDR softwa
10. config file SNDR set set name Chapter 3 Sun SNDR Software Commands 37 Waiting for Synchronization to Finish Executing Use the sndradm w command in one of the following situations m When you need to be sure that the copy or update operation is finished executing before you use a primary application like a database application or another Sun SNDR software command on the specified volume set or I O group m Before disabling a volume set so that any write or copy operations can finish executing m Aspartofa script executing Sun SNDR software commands sndradm w This command enables you to make the Sun SNDR software wait until an in progress copy or update synchronization operation finishes executing It prevents another Sun SNDR software command from executing on the specified volume set or I O group Syntax sndradm w g io groupname C tag n config file SNDR set set name 38 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Stopping Sun SNDR Software Operations and Starting Logging Use the sndradm 1 command to start status and scoreboard logging on enabled volume sets and I O groups Note To resume Sun SNDR software operations after using the sndradm 1 command use the sndradm m command to perform a full resynchronization or the sndradm u command to perform an update resynchronization Note also that when issued from the secondary host the sndradm 1
11. inaccessible from other machines in a cluster To compensate you can use a caching array such as the Sun StorEdge A3500 disk array Note The Sun StorEdge data services software volumes such as those used with the Sun SNDR and Instant Image Version 3 0 Software do not fail over in a Sun Cluster 2 2 environment Chapter 1 Overview 7 8 In a Sun Cluster 2 2 environment the Sun StorEdge Version 3 0 data services software requires that the following patches be installed Solaris 7 operating environment Patch number 109209 06 Solaris 8 operating environment Patch number 109210 05 Before starting a Sun Cluster ensure that the Sun SNDR volume sets do not have a copy or update operation in progress During a failover or takeover operation on a Sun Cluster logical host the list of all volumes being deported is checked to determine whether they are part of one or more Sun StorEdge data services software volume sets For each volume that is part of such a volume set the following occurs m All processes accessing these volumes or raw devices will be politely killed m All mounted file systems nfs ufs or VxFS will be unshared or unmounted m The Sun StorEdge data services software volume sets will be disabled and then removed from the data services and Storage Volume SV driver configuration After a Sun Cluster failover or takeover operation the volume sets remain disabled and require manual reconfiguration using the
12. v To Permanently Terminate the Sun SNDR Software Remote Replication and Resynchronization Services From both hosts use this command host1 sndradm d g io groupname C tag n config file SNDR set set name Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 87 88 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Glossary asynchronous replication data service disk full synchronization health monitor HDA I O group local mirrors Asynchronous replication confirms to the originating host that the primary I O transaction is complete before updating the remote image Asynchronous replication is used when the distance between primary and secondary sites might introduce prohibitive latency times to the synchronous operations One of the Sun StorEdge software components Sun StorEdge Network Data Replicator Fast Write Cache Instant Image or Target Emulation A host view of the logical storage device Also referred to as volumes Several host volumes can be physically stored in a single head disk assembly HDA Alternatively a single host volume can be spread striped across multiple HDAs The Sun SNDR software options are performed on discrete logical volumes rather than on physical HDAs A complete volume to volume copy which is the most time consuming of the synchronization operations In most cases a secondary volume is synchroni
13. Chapter 3 Sun SNDR Software Commands 57 58 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 CHAPTER 4 Using The Sun SNDR Software to Restore Volumes and Sites You must enable the Sun SNDR software at the primary and secondary sites before attempting the tasks in this chapter See Chapter 3 for information on the command syntax The topics in this chapter include Preparing to Use the Sun SNDR Software on page 60 Full Forward Synchronization Establishing Replicated Images for the First Time on page 64 Handling Interruptions on page 66 Restoring Volumes After a Secondary Site Failure on page 71 Rehearsing Disaster Recovery on page 74 Primary Site Failures on page 78 Recovering From a Primary Site Disaster on page 82 Reverse Synchronization Updating the Primary Site From the Secondary Site on page 83 Full Reverse Synchronization Completely Restoring a Primary Site From the Secondary Site on page 85 Disabling Remote Replication on page 86 59 Preparing to Use the Sun SNDR Software This section describes several issues you need to consider before you start using the Sun SNDR software These topics are as follows m Definition of Primary and Secondary Sites and Network Link Type on page 60 m Selecting Volumes on page 61 m Using the Storage Volume Interface on page 62 m Monitoring Sun SNDR Softw
14. Remove the Volumes From SV Control and the Sun StorEdge Configuration on page 31 Use the sndradm d command when the primary and secondary volumes no longer need to be associated with each other as Sun SNDR software volume sets This command discards any active Sun SNDR software scoreboard logs See Enabling the Sun SNDR Software on page 28 to re enable Sun SNDR software replication and Starting a Full Synchronization Copy Between Volumes on page 34 to reestablish identical replicated sets sndradm d When you issue this command the Sun SNDR software terminates all replication services between the specified primary and secondary volumes and discontinues the relationship between these volume sets It also discards any active scoreboard logs that track temporary differences between primary and secondary volumes Note This command also removes the information for the specified set from the Sun StorEdge data services Syntax sndradm d g io groupname C tag n config file SNDR set set name Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 v To Remove the Volumes From SV Control and the Sun StorEdge Configuration The Sun SNDR sndradm e and sndradm E commands automatically add configured volumes to the SV driver s configuration During the disabling of the Sun SNDR volumes the volumes are not automatically removed from the Sun StorEdge configuration Al
15. SNDR Version 2 0 software See Configuration Files from Version 2 0 on page 15 Syntax sndradm I a master vol shadow vol bitmap vol where master vol shadow vol and bitmap vol are the full path to the raw device nodes for configured Instant Image volumes See the Sun StorEdge Instant Image Software 3 0 System Administrator s Guide for more information Note Before the usr opt SUNWrdc lib sndrsyncd daemon performs an update synchronization after a network link or machine failure it creates a matching Instant Image volume group entry After the update finishes executing you may choose to delete this entry with the usr opt SUNWscm sbin iiadm d command However do not delete this entry so that the daemon can use it in subsequent resynchronizations involving the Instant Image software See Autosynchronization With Instant Image Software Configured on page 69 32 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 sndradm I d This command deletes an Instant Image volume group entry from the data services Syntax sndradm I d master vol shadow vol bitmap vol where master vol shadow vol and bitmap vol are the full path to the raw device nodes for configured Instant Image volumes See the Sun StorEdge Instant Image 3 0 System Administrator s Guide for more information Chapter 3 Sun SNDR Software Commands 33 Starting a Full Synchronization Copy Between Volumes
16. StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Code Samples CODE EXAMPLE 3 1 scmadm S Link Status Display 54 CODE EXAMPLE 3 2 Sample scmadm s Display Cache Statistics 56 CODE EXAMPLE 3 3 Sample scmadm s Display Cumulative Cache Statistics 56 xi xii Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Tables TABLE 1 1 TABLE 1 2 TABLE 2 1 TABLE 3 1 TABLE 3 2 TABLE 3 3 TABLE 3 4 TABLE 3 5 TABLE 3 6 TABLE 3 7 TABLE 3 8 Sun SNDR Software Features 3 Getting Started Task Summary 11 Optional Configuration File Format Fields 14 rdcadm and sndradm Command Differences Between Sun SNDR Software Version 2 0 and Version 3 0 21 Command Options 23 Sun SNDR Software Tasks and Related Command Parameters 25 Which Host to Issue Commands From 27 Keys Used in scmadm Display 51 scmadm S Options 52 Fields for Sun SNDR Software Screen Display 53 scmadm S Fields 55 xiii xiv Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Preface The Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide describes the Sun StorEdge Network Data Replicator Sun SNDR software and its use This guide is intended for system administrators who have experience with the Solaris operating environment and related disk storage systems Before You Read This Book To fully use the information in this
17. Sun SNDR software before you can use them Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Sun StorEdge Instant Image Software The Sun StorEdge Instant Image Version 3 0 software is an optional software component You can combine the Sun SNDR software with volumes from Instant Image software to create multiple copies of each device See Adding and Deleting Instant Image Software Volumes on page 32 The Instant Image software is a point in time volume copy data service for the Solaris operating environment With Instant Image software you create a volume pair a point in time logical volume copy shadow from the original logical volume master which you specify Once the shadow is established you can read from and write to this shadow volume and the master volume The Instant Image software is best used just before you perform a resynchronization to ensure that a consistent copy of data exists In this case if the resynchronization is interrupted you at least have a copy of known good data that is usable During the resynchronization process of updating the local and remote sites the data on a secondary Sun SNDR volume is temporarily inconsistent with the primary volume The secondary volume cannot be relied on for data recovery Consistency is restored when the resynchronization is complete To ensure data integrity use Instant Image software regularly to create a point in time copy of data
18. at the primary When it is time to bring the primary back into service the scoreboards can be used to refresh the primary contents from the current secondary images v To Start the Reverse Synchronization From the Secondary to the Primary Volumes On the primary host use this command hostl sndradm u r g io groupname C tag n config file SNDR set set name Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 83 84 Data Flow FIGURE 4 7 shows a reverse update resynchronization from the secondary system to its primary system 1 The Sun SNDR software on host 1 retrieves the secondary scoreboard 1R from host2 for one of the Sun SNDR software managed volumes affected by the interruption The Sun SNDR software on host1 requests the blocks updated during the interruption from the up to date secondary volume of host 2 The data might already be resident in host 2 s data cache or it might require secondary disk access The Sun SNDR software on host 2 transmits the updated blocks 3R to host 1 Sun SNDR software region of cache using the intersite link The Sun SNDR software on host1 refreshes its stale image with the updated blocks The Sun SNDR software on host1 revises the scoreboard to track the remote update All steps repeat until the primary volume is up to date Site A Primary Remote Site B Secondary Disk Dis
19. command does not work on the secondary volume for any volume that is currently synchronizing sndradm 1 This command enables you to stop replication between primary and secondary volumes and to start scoreboard logging on these volumes The Sun SNDR software will continue logging if the operations of a volume set or I O group are interrupted If all volume sets in an I O group are replicating meaning that the secondary volumes contain a valid point in time copy of the corresponding primary volumes when one volume set enters logging mode all other sets in the group will enter logging mode automatically This scheme ensures that the secondary volumes will contain a valid point in time copy Syntax sndradm 1 g io groupname C tag n config file SNDR set set name Chapter 3 Sun SNDR Software Commands 39 Assigning a New Scoreboard Bitmap to a Volume Set Use the sndradm R b command when you need to assign a new scoreboard bitmap to a volume set Tip If you upgraded from the Sun SNDR Version 2 0 software and used bitmap files instead of bitmap volumes in Version 2 0 use this command to assign new primary and secondary host bitmap volumes to the Sun SNDR volume set This command copies any data from the bitmap file to the bitmap volume The Sun StorEdge Network Data Replicator 3 0 Installation Guide describes this procedure sndradm R Db This command enables you to assign a new scoreboard bitmap t
20. n config file SNDR set set name 44 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Updating the Volume Set Configuration Use the sndradm R f command to change the current volume sets being operated on by the Sun SNDR software This command is useful when you use a configuration file and have made changes to it The fields for the configuration file specified using the f option are similar to those in the SNDR set described in TABLE 3 2 phost pdev pbitmap shost sdev sbitmap ip synclasync g io groupname C tag See Using a Configuration File on page 14 and the rdc cf man page for more information sndradm R f This command enables you to update or reconfigure the current volume set configuration from a specified configuration file Syntax sndradm R f config file g io groupname C tag n Chapter 3 Sun SNDR Software Commands 45 Updating the Disk Cluster Tag Name Caution Do not install or use the Sun StorEdge Version 3 0 Core and data services software on servers in a Sun Cluster 3 0 environment The Version 3 0 software is not co existent with the Sun Cluster 3 0 environment The Version 3 0 software is co existent in the Sun Cluster 2 2 environment where it will not interfere with failover The Version 3 0 core and data services software is cluster aware in the Sun Cluster 3 0 Update 1 environment and provides high availability for the Sun StorEd
21. the Sun SNDR software converts your Version 2 0 configuration files to the latest format during installation The Sun SNDR Version 2 0 software uses three configuration files The default configuration file named etc opt SUNWrdc rdc cf is used to specify all volumes under the Sun SNDR software control You could also create a customized configuration file depending on your server connection and disaster recovery plans in the Sun SNDR software Version 2 0 if this customized configuration file is named etc opt SUNWrdc rdc cf the Sun SNDR 3 0 installation process will use it If it is not named rdc cf include this information in the rdc cf file so that you can use it in Version 3 0 The etc opt SUNWrdc rdc_ii cf configuration file is used to list all secondary volumes on which Sun StorEdge Instant Image software was enabled by the rdc_ii enable script The etc opt SUNWspsv sv cf Storage Volume SV driver interface file is used to place Sun SNDR software volumes under SV control Sun SNDR software Version 3 0 enables you to keep using the same volumes that you used with the Sun SNDR software Version 2 0 as specified in the rdc cf rdc_ii cf and sv cf configuration files When you remove the Version 2 0 software the removal process using pkgrm 1M preserves the rdc cf rdc_ii cf and sv cf configuration files in their original locations When the Sun SNDR software Version 3 0 installation process finds them in their original locations i
22. using a specific secondary volume FIGURE 1 1 shows one primary and three secondary host volumes and therefore three volume sets A and B1 A and B2 and A and B3 Tip You can group one to many sets that share a common primary volume in a single I O group to operate on all sets simultaneously instead of issuing a separate command for each set See Sun SNDR Commands and I O Group Operations on page 22 In a multihop set the secondary host volume of one volume set can be the primary host volume of another volume set FIGURE 1 1 shows one primary and one secondary host volume the secondary host volume B becomes the primary host volume A1 to the secondary host volume B1 Secondary host volume To B1 Oneto Many a dev rdsk c0t0d0s5 A Primary host volume Secondary host volume B2 1 dev rdsk c0t0d0s5 dev rdsk c0t0d0s7 Secondary host volume B3 dev rdsk c0t0d0s9 Multihop Primary host volume Secondary host volume Secondary host volume dev rdsk c0t0d0s5 dev rdsk c0t0d0s5 dev rdsk c0t0d0s5 A B a1 B1 One volume set Another volume set A Primary host volume B Secondary host volume FIGURE 1 1 One to Many and Multihop Volume Sets 6 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Command Compatibility With the Sun SNDR Software Version 2 0 The Sun SNDR Version 3 0 software command line interface CLI usr opt SUNWesm sbin sndradm is generally com
23. 0t117d0s3 SS atmsi rdsk clt6d0s3 sync ma dsk c0t115d0s3 RER atmsi dsk clt9d0s3 sync ma dsk c0t116d0s3 D atmsi dsk clt6d0s3 sync ma dsk c0t96d0s3 atmsi rdsk clt0d0s3 replicating partition recovery needed recovery completed dev rdsk c0t117d0s3 Ji 29 2535 ERS SABA NRA CAA 70 47 dev rdsk c0t115d0s3 291605 ERE AAA RAE AAS 70 84 dev rdsk c0t116d0s3 11 2938 FETTE RARE 70 62 54 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Example scmadm S Screen Display The scmadm S statistics include the fields described in TABLE 3 8 Use the M key to toggle between these statistics and the Sun SNDR software statistics Use the T key to display the cumulative cache statistics generated since the last time the counters were reset Type scmadm S z to reset the counters The sample displays in CODE EXAMPLE 3 2 and CODE EXAMPLE 3 3 contain the cache statistics and cumulative cache statistics displays TABLE 3 8 scmadm S Fields Field Description cd Specifies the cache descriptor number cached partition disk io cache write blocks accesses s read s write s Sreadh Swriteh cachesize blocksize Write blocks available Specifies the disk partition being monitored Displays the number of Kbytes per second read from or written to physical disks Displays the number of Kbytes per second read from or written to data cach
24. 1 2 4 ay v score board gt i3R 3 Up to date Stale remote 5 local disk ATM disk n 68 Indicates one transmit and one receive fiber used in intersite fiber link FIGURE 4 2 Update Synchronization of a Secondary Volume Set Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Autosynchronization After an Interruption Note See the command descriptions for Toggling the Sun SNDR Software Autosynchronization State on page 49 and Setting the Asynchronous Queue on page 50 The Sun SNDR software synchronization daemon usr opt SUNWrdc lib sndrsyncd starts when the Sun SNDR software starts by default autosynchronization is disabled You enable it on a volume set basis using the sndradm a command The daemon monitors the existing Sun SNDR software configuration and attempts to resynchronize the specified volumes if the secondary system reboots or a link failure occurs You can initiate automatic resynchronizations only on the primary system If the secondary host is enabled the update synchronization operations are started on the primary system to update all the specified secondary hosts Autosynchronization With Instant Image Software Configured Note See the command description for Adding and Deleting Instant Image Software Volumes on page 32 The usr opt SUNWrdc lib sndrsyncd daemon aut
25. Book titles new words or Read Chapter 6 in the User s Guide terms words to be These are called class options emphasized You must be root to do this Command line variable To delete a file type rm filename replace with a real name or value In syntax brackets indicate scmadm d sec r n n L n z that an argument is optional arg arg In syntax braces and pipes sndradm R Db pls indicate that one of the arguments must be specified Shell Prompts Shell Prompt C shell C shell superuser Bourne shell and Korn shell Bourne shell and Korn shell superuser machine_name machine_name Preface xvii Related Documentation Application Title Part Number man pages sndradm N A scmadm svadm iiadm Latest information Sun StorEdge Network Data Replicator 3 0 Release 806 7513 Notes Sun StorEdge Instant Image 3 0 Release Notes 806 7678 Installation and User Sun StorEdge Network Data Replicator 3 0 806 7514 Installation Guide Sun StorEdge Instant Image 3 0 Installation Guide 806 7675 SunATM 3 0 Installation and User s Guide 805 0331 Sun ATM 4 0 Installation and User s Guide 805 6552 Sun Gigabit Ethernet FC AL P Combination Adapter 806 2385 Installation Guide Sun Gigabit Ethernet S 2 0 Adapter Installation and 805 2784 User s Guide Sun Gigabit Ethernet P 2 0 Adapter Installation and User s Guide 805 2785 Sun Enterprise 10000 InterDomain Networks User 806 4131 Guide Syst
26. NS amp Sun microsystems Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide Sun Microsystems Inc 901 San Antonio Road Palo Alto CA 94303 4900 U S A 650 960 1300 Part No 806 7512 10 June 2001 Revision A Send comments about this document to docfeedback sun com Copyright 2001 Sun Microsystems Inc 901 San Antonio Road Palo Alto CA 94303 4900 U S A All rights reserved This product or document is distributed under licenses restricting its use copying distribution and decompilation No part of this product or document may be reproduced in any form by any means without prior written authorization of Sun and its licensors if any Third party software including font technology is copyrighted and licensed from Sun suppliers Parts of the product may be derived from Berkeley BSD systems licensed from the University of California UNIX is a registered trademark in the U S and other countries exclusively licensed through X Open Company Ltd Sun Sun Microsystems the Sun logo AnswerBook2 docs sun com Sun StorEdge SunATM and Solaris are trademarks registered trademarks or service marks of Sun Microsystems Inc in the U S and other countries All SPARC trademarks are used under license and are trademarks or registered trademarks of SPARC International Inc in the U S and other countries Products bearing SPARC trademarks are based upon an architecture developed by Sun Microsystems Inc
27. P IP Continue remote data access despite local disk failure depending on how the Sun SNDR software is configured See Using the Sun StorEdge Data Services Software in a Sun Cluster Environment on page 7 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Volume Size Requirements Note Volume size checking is performed only when you initiate a synchronization or resynchronization The primary and secondary volumes must be the same size If you initiate a resynchronization on a Sun SNDR software volume set where the secondary is larger than the primary a warning message appears but the initiation is allowed to continue If you initiate a resynchronization on a Sun SNDR software volume set where the secondary volume is smaller than the primary the Sun SNDR software fails with an error Chapter 1 Overview 5 One to Many and Multihop Volume Sets The Sun SNDR software enables you to create one to many and multihop volume sets In a one to many volume set you can replicate data from one primary volume to many secondary volumes residing on one or more hosts One primary and each secondary host volume is a single volume set each secondary volume requires its own unique secondary bitmap volume When you perform a forward resynchronization you can synchronize one volume set or all volume sets in this case issue a separate command for each set You can also update the primary volume by
28. Set and I O Group Status on page 41 m Displaying a List of Current Volume Sets and Group Names on page 42 19 m Displaying Link Status on page 43 m Moving a Volume Set to a Different I O Group on page 44 m Updating the Volume Set Configuration on page 45 m Updating the Disk Cluster Tag Name on page 46 m Resetting the Replication Mode of a Volume Set on page 47 m Toggling the Sun SNDR Software Autosynchronization State on page 49 m Setting the Asynchronous Queue on page 50 m Getting Sun SNDR Software and Storage Cache Statistics The scmadm Command on page 51 20 Command Option and Parameter Summary The usr opt SUNWesm sbin sndradm command uses the options in TABLE 3 2 and the parameters in TABLE 3 3 Note If you use a command without specifying any volume set arguments the command operates on all Sun SNDR volume sets Log File The var opt SUNWesm ds log file contains operation log messages for the Sun SNDR commands Command Compatibility with Version 2 0 The Sun SNDR software Version 3 0 sndradm command is generally compatible with the Sun SNDR software Version 2 0 rdcadm command The Version 3 0 sndradm command is also linked to the rdcadm command so that if your existing scripts reference the rdcadm command the Version 3 0 software will use the sndradm command to perform the specified operations TABLE 3 1 shows the instances where the two comma
29. TATION EST FOURNIE EN L ETAT ET TOUTES AUTRES CONDITIONS DECLARATIONS ET GARANTIES EXPRESSES OU TACITES SONT FORMELLEMENT EXCLUES DANS LA MESURE AUTORISEE PAR LA LOI APPLICABLE Y COMPRIS NOTAMMENT TOUTE GARANTIE IMPLICITE RELATIVE A LA QUALITE MARCHANDE A L APTITUDE A UNE UTILISATION PARTICULIERE OU A L ABSENCE DE CONTREFA ON QS aos ca Adobe PostScript Contents Preface xv Overview 1 Sun SNDR Software Description 2 Features 3 Volume Size Requirements 5 One to Many and Multihop Volume Sets 6 Command Compatibility With the Sun SNDR Software Version 2 0 7 Using the Sun StorEdge Data Services Software in a Sun Cluster Environment 7 Sun StorEdge Instant Image Software 9 Network Protocols 9 What Happens When Volume Sets Do Not Match 10 Getting Started Task Summary 11 Configuration Files and Bitmaps 13 Using a Configuration File 14 Configuration Files from Version 2 0 15 Bitmaps 16 Bitmap Size Requirements 16 Using More Than 64 Sun SNDR Software Volume Sets 17 iv 3 Sun SNDR Software Commands 19 Command Option and Parameter Summary 20 Log File 20 Command Compatibility with Version 2 0 20 Sun SNDR Commands and I O Group Operations 22 Sun SNDR Commands and Sun Cluster Operations 22 Configuration File Format Using f config file 23 Which Host Do I Issue Commands From 27 Enabling the Sun SNDR Software 28 Using a Volume Set Name 28 sndradm e 28 sndradm E 29 Disabling the Sun SNDR Software 30 sn
30. The OPEN LOOK and Sun Graphical User Interface was developed by Sun Microsystems Inc for its users and licensees Sun acknowledges the pioneering efforts of Xerox in researching and developing the concept of visual or graphical user interfaces for the computer industry Sun holds anon exclusive license from Xerox to the Xerox Graphical User Interface which license also covers Sun s licensees who implement OPEN LOOK GUIs and otherwise comply with Sun s written license agreements Federal Acquisitions Commercial Software Government Users Subject to Standard License Terms and Conditions DOCUMENTATION IS PROVIDED AS IS AND ALL EXPRESS OR IMPLIED CONDITIONS REPRESENTATIONS AND WARRANTIES INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE OR NON INFRINGEMENT ARE DISCLAIMED EXCEPT TO THE EXTENT THAT SUCH DISCLAIMERS ARE HELD TO BE LEGALLY INVALID Copyright 2001 Sun Microsystems Inc 901 San Antonio Road Palo Alto CA 94303 4900 Etats Unis Tous droits r serv s Ce produit ou document est distribu avec des licences qui en restreignent l utilisation la copie la distribution et la d compilation Aucune partie de ce produit ou document ne peut tre reproduite sous aucune forme par quelque moyen que ce soit sans l autorisation pr alable et crite de Sun et de ses bailleurs de licence s il y en a Le logiciel d tenu par des tiers et qui comprend la technologie relative aux polices de cara
31. adm R m synclasync C tag n config file SNDR set set name Considerations m Mixed mode I O group Creating a mixed I O group where mirroring modes are asynchronous for one set and synchronous for another set is not allowed m Volume set requirements All volume sets in the I O group must have the same primary host secondary host and mirroring mode Chapter 3 Sun SNDR Software Commands 47 v To Remove a Volume Set from a Group and Change Its Replication Mode 1 Remove the volume set from its group sndradm R g SNDR set set name 2 Change the volume set replication mode See also Syntax on page 47 sndradm R m synclasync set name 3 If desired add the volume sets you have changed to an I O group See also Moving a Volume Set to a Different I O Group on page 44 sndradm R g io groupname f config file SNDR set set name 48 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Toggling the Sun SNDR Software Autosynchronization State Use the sndradm a command to enable or disable autosynchronization sndradm a This command enables or disables the Sun SNDR software autosynchronization If Sun SNDR software autosynchronization is enabled on the primary host the synchronization daemon attempts to resynchronize if the system reboots or link failures occur The default state is disabled Syntax
32. also choose the bitmap mode setting of 1 to improve error recovery Bitmap Size Requirements The bitmap size can be calculated using the following formula m 1 Kbytes 4 Kbytes per Gbyte of device storage space For example a 2 Gbyte data device requires a bitmap size of 9 Kbytes You can create bitmaps that are larger than the calculated size Also round up any partial Gbyte counts to the next Gbyte 16 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Using More Than 64 Sun SNDR Software Volume Sets Note After editing the usr kernel drv rdc conf file reboot your server If you configure more than 64 Sun SNDR software volume sets you must edit the rdc_max_sets field in the usr kernel drv rdc conf file on each machine running the Sun SNDR software The default number of configured volume sets is 64 For example to use 128 sets change the file as follows note the semicolon at the end of the rdc_max_sets field rdc_max_sets Configure the maximum number of RDC sets that can be enabled on this host The actual maximum number of sets that can be enabled will be the minimum of this value and nsc max devices see nsctl conf at the time the rdc kernel module is loaded rdc_max_sets 128 Chapter 2 Configuration Files and Bitmaps 17 18 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 CHAPTER 3 Su
33. ap Volume partition or file in which the bitmap scoreboard log of the primary partition is stored Specify full path names only for example dev rdsk c0t1d0s2 shost Server on which the secondary volume resides sdev Secondary volume partition Specify full path names only for example dev rdsk c0t1d0s2 sbitmap Volume partition or file in which the bitmap scoreboard log of the secondary partition is stored Specify full path names only for example dev rdsk c0t1d0s2 ip Specifies the network protocol Chapter 3 Sun SNDR Software Commands 23 24 TABLE 3 2 Command Options Continued Option Definition set name g io groupname C tag sync async Sun SNDR software operating mode sync is the Sun SNDR software mode where the I O operation is not confirmed as complete until the remote volume has been updated async is the Sun SNDR software mode where the primary host I O operation is confirmed as complete before updating the remote volume g io groupname Specifies which I O group the volume set belongs to You can use the C tag and C tag options in a Sun Cluster 3 0 Update 1 environment only If you accidentally use these options in a non Sun Cluster 3 0 environment the Sun SNDR operation does not execute C tag For operation within a Sun Cluster 3 0 Update 1 environment only C tag specifies the disk group name or resource tag of the local data and bitmap volumes in c
34. are Operations on page 62 m Mutual Backup Considerations on page 62 m Using the Sun SNDR Software With Sun StorEdge Instant Image Software on page 63 Definition of Primary and Secondary Sites and Network Link Type In the examples in this chapter Site A host 1 is the local primary host site and machine name and Site B host 2 is the remote secondary host site and machine name respectively Depending on the example either site can be the primary or secondary of the remote copy operation As shown in TABLE 3 4 you must perform all synchronization operations from the primary host session Note The diagrams in this section show the network link type as ATM Although the Sun SNDR software is most likely to be used with SunATM link level interfaces the Sun SNDR software can be used with any Sun supported link level interface that is TCP IP capable such as Gigabit Ethernet Gigabit Ethernet Fibre Channel and others 60 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Selecting Volumes The first planning step is to determine which volumes to include in the remote replication operations The secondary volume must be as large as the primary volume It is important to balance remote accessibility and recoverability against capacity usage and I O response time Generally include the following critical volumes in the remote replication configuration m Databases and database mana
35. ases where this is not implied by the name of the volume For example dev rdsk md dg vol and dev vx rdsk dg vol both indicate a disk group name of dg It is the responsibility of the user to ensure that the cluster tag specified to the Sun SNDR software matches the appropriate cluster resource group tag and to keep all installed data services updated in the event of cluster resource group reconfigurations Name of the Sun SNDR software volume set as assigned by the Sun SNDR software The Sun SNDR software assigns a default volume set name of shost sdev where shost is the secondary host name and sdev is the secondary volume partition name separated by a colon Name of the I O group containing the collection of Sun SNDR software volume sets Specifying g io groupname limits any operation performed to the sets in the named io groupname You can use the C tag and C tag options in a Sun Cluster 3 0 Update 1 environment only If you accidentally use these options in a noncluster environment the Sun SNDR operation does not execute Specifying C tag limits any operation performed to the sets in the named tag cluster resource tag Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 TABLE 3 3 Sun SNDR Software Tasks and Related Command Parameters Operation Command For Detailed Information See Enable the Sun SNDR software for the specified set sndradm E Enabling the Sun SNDR sync
36. assigns a default volume set name of shost sdev If you specify no arguments the Sun SNDR software displays all configured volume sets however for best display results specify a volume set using shost sdev Chapter 3 Sun SNDR Software Commands 43 Moving a Volume Set to a Different I O Group Use the sndradm R g command to move volume sets to a different I O group To move multiple sets to a single io groupname keep the io groupname the same and specify different set names on the command line Tip You can also move all volume sets in one I O group to another I O group Use the command as follows sndradm g io groupname R g new io groupname To move selected sets from an I O group enter the volume set information in a file and use the f config file option Tip To remove a volume set from an I O group use double quotes to specify a null group used with the g command option as follows sndradm R g SNDR set set name To remove all volume sets from an I O group sndradm R g g io groupname To remove selected sets from an I O group enter the volume set information in a file and use the f config file option sndradm R g This command enables you to move volume sets to a different I O group thereby updating an existing I O group You must specify at least one set name Enter this command on the primary and secondary hosts Syntax sndradm R g io groupname g io groupname C tag
37. at both sites See the Instant Image documentation listed in Related Documentation on page xvili Network Protocols Although the Sun SNDR software is most likely to be used with SunATM link level interfaces the Sun SNDR software can be used with any Sun supported link level interface that is TCP IP capable such as Gigabit Ethernet Gigabit Ethernet Fibre Channel and others When using ATM ensure that the configuration supports TCP IP by using either Classical IP or LAN Emulation For more information on configuring the SunATM interface for these protocols refer to the Sun ATM Installation and User s Guide See the network protocol manuals listed in Related Documentation on page xviii for more information about other protocols Chapter 1 Overview 9 What Happens When Volume Sets Do Not Match Physical separation provides highly available storage configurations but requires special attention to logistics Intersite link outages component failures and other situations temporarily cause the primary and secondary volume to be out of sync The Sun SNDR software uses several logging and resynchronization techniques to reestablish mirror copies m Full synchronization that is a complete volume to volume copy is used when the remote volume specified for redundancy is newly formatted or its contents are unknown m Update resynchronization provides a streamlined way to make remote sets match if their changes have b
38. ct res est prot g par un copyright et licenci par des fournisseurs de Sun Des parties de ce produit pourront tre d riv es des syst mes Berkeley BSD licenci s par l Universit de Californie UNIX est une marque d pos e aux Etats Unis et dans d autres pays et licenci e exclusivement par X Open Company Ltd Sun Sun Microsystems le logo Sun AnswerBook2 docs sun com Sun StorEdge SunATM et Solaris sont des marques de fabrique ou des marques d pos es ou marques de service de Sun Microsystems Inc aux Etats Unis et dans d autres pays Toutes les marques SPARC sont utilis es sous licence et sont des marques de fabrique ou des marques d pos es de SPARC International Inc aux Etats Unis et dans d autres pays Les produits portant les marques SPARC sont bas s sur une architecture d velopp e par Sun Microsystems Inc L interface d utilisation graphique OPEN LOOK et Sun a t d velopp e par Sun Microsystems Inc pour ses utilisateurs et licenci s Sun reconna t les efforts de pionniers de Xerox pour la recherche et le d veloppement du concept des interfaces d utilisation visuelle ou graphique pour l industrie de l informatique Sun d tient une licence non exclusive de Xerox sur l interface d utilisation graphique Xerox cette licence couvrant galement les licenci s de Sun qui mettent en place l interface d utilisation graphique OPEN LOOK et qui en outre se conforment aux licences crites de Sun LA DOCUMEN
39. dm S 51 Example scmadm S Screen Display 53 Example scmadm S Screen Display 55 Contents v 4 Using The Sun SNDR Software to Restore Volumes and Sites 59 Preparing to Use the Sun SNDR Software 60 Definition of Primary and Secondary Sites and Network Link Type 60 Selecting Volumes 61 Using the Storage Volume Interface 62 Monitoring Sun SNDR Software Operations 62 Mutual Backup Considerations 62 Using the Sun SNDR Software With Sun StorEdge Instant Image Software 63 Full Forward Synchronization Establishing Replicated Images for the First Time 64 Existing Primary and Newly Formatted Secondary Volumes 64 v To Fully Synchronize Specific Remote Volumes While Applying New Updates 64 Data Flow 65 Handling Interruptions 66 Primary Logging During Interruptions 66 Forward Resynchronization Update Resynchronizing Volumes After an Interruption 66 Y To Enable Update Synchronization 67 Data Flow 68 Autosynchronization After an Interruption 69 Autosynchronization With Instant Image Software Configured 69 Restoring Volumes After a Secondary Site Failure 71 Restoring a Failed Secondary Volume 71 v To Restore a Volume Set at a Remote Site 71 Data Flow 72 Restoring a Failed Secondary Server 73 v To Perform an Update Operation 73 vi Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 v ToPerformaFullSynchronization 73 Switching to an Alternate Fiber ATM Only 73 Rehearsing Disaster Recovery 74 Rehear
40. document you must have thorough knowledge of the topics discussed in these books m Sun StorEdge Network Data Replicator 3 0 Installation Guide m Sun StorEdge Network Data Replicator 3 0 Release Notes The Sun SNDR software must be installed as described in the installation and release documentation XV How This Book Is Organized Chapter 1 provides general information about the Sun SNDR software and describes the Sun SNDR software terminology Chapter 2 describes the Sun SNDR software configuration and bitmapvolumes Chapter 3 describes the Sun SNDR software commands Chapter 4 explains the Sun SNDR software operations including synchronization recovery rehearsals and mirrored partitions The Glossary contains definitions of terms used in this document xvi Using UNIX Commands This document may not contain information on basic UNIX commands and procedures such as shutting down the system booting the system and configuring devices Refer to the software documentation that you received with your system Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Documentation Conventions Typeface or Symbol Meaning Examples AaBbCc123 The names of commands Edit your login file files and directories Use ls a to list all files on screen computer output You have mail AaBbCc123 What you type when su contrasted with on screen Password computer output AaBbCc123
41. dradm d 30 v To Remove the Volumes From SV Control and the Sun StorEdge Configuration 31 Adding and Deleting Instant Image Software Volumes 32 sndradm I a 32 sndradm I d 33 Starting a Full Synchronization Copy Between Volumes 34 sndradm m 34 sndradm m r 35 Starting a Resynchronization Update Between Volumes 36 sndradm u 36 sndradm u r 37 Waiting for Synchronization to Finish Executing 38 sndradm w 38 Stopping Sun SNDR Software Operations and Starting Logging 39 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 sndradm 1 39 Assigning a New Scoreboard Bitmap to a Volume Set 40 sndradm R b 40 Displaying Volume Set and I O Group Status 41 sndradm p 41 sndradm P 41 Displaying a List of Current Volume Sets and Group Names 42 sndradm i 42 Displaying Link Status 43 sndradm H 43 Moving a Volume Set to a Different I O Group 44 sndradm R g 44 Updating the Volume Set Configuration 45 sndradm R f 45 Updating the Disk Cluster Tag Name 46 sndradm R C 46 Resetting the Replication Mode of a Volume Set 47 sndradm R m 47 v To Remove a Volume Set from a Group and Change Its Replication Mode 48 Toggling the Sun SNDR Software Autosynchronization State 49 sndradm a 49 Setting the Asynchronous Queue 50 sndradm W 50 sndradm F 50 Getting Sun SNDR Software and Storage Cache Statistics The scmadm Command 51 scma
42. e dirty the number of dirty cache blocks that have not been queued for destaging todisk the number of blocks that have been queued for destaging and are waiting to be written to disks The blocks displayed here are eventually moved to disk io writes Displays the number of I O operations reads per second writes per second serviced by the cache per second The accesses s total is the sum of the hits and misses Displays the number of read requests hits serviced per second misses s Displays the number of read misses per second Displays the number of write requests serviced per second misses s Displays the number of write misses per second Displays the percent of reads that are cache hits Displays the percent of writes that are cache hits Displays the cache size Displays the blk size Displays the available write cache in blocks Net n in the field represents each network Chapter 3 Sun SNDR Software Commands 55 TABLE 3 8 scmadm S Fields Continued Field Description LRU stats Displays the least recently used LRU algorithm statistics Blocks the number of cache blocks in the LRU always the total number of blocks in the cache This figure stays constant Requeued unused Opt imized cache blocks not requeued to the tail of the LRU Total Cache Displays the size of system memory that is used by the cache when Memory Usage cache starts Total Stats Displays the size of syste
43. e June 2001 Configuration File Format Using f config file The fields for the configuration file specified using the f option are similar to those in the SNDR set described in Command Options on page 23 phost pdev pbitmap shost sdev sbitmap ip synclasync g io groupname C tag See Using a Configuration File on page 14 and the rdc cf man page for more information TABLE 3 2 Command Options Option Definition en Does not prompt the user after starting a Sun SNDR software operation using sndradm The default is to prompt and request a response For example after starting a full synchronization from the primary to secondary volumes the Sun SNDR software prompts Overwrite secondary with primary Y N N f config file Specifies a configuration file defining the Sun SNDR software volume sets If you do not specify a config file SNDR set or set name the command acts on all volume sets SNDR set Specifies the complete Sun SNDR software set configuration information If SNDR set is not specified on the command line the information is retrieved from a configuration file you specify using the f config file option The SNDR set format is as follows phost pdev pbitmap shost sdev sbitmap ip sync async g io groupname C tag phost Server on which the primary volume resides pdev Primary volume partition to be copied Specify full path names only for example dev rdsk c0t1d0s2 pbitm
44. e request to its local volumes 2 The write data D is placed into host 2 data cache 3 The Sun SNDR software keeps a scoreboard for each Sun SNDR software managed volume to indicate changes from the last known image synchronized with hostl These scoreboard logs might be used later to overwrite the changed segments with the most recent data from the primary volumes 4 Software on host2 destages the write data to the local volume Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 75 Site A Primary Disk Cache HBA host1 Host ATM Disk HBA Cache host2 2 Indicates one transmit I D lt 1 and one receive fiber used in intersite fiber link 4 3 v score board Modified recovery disk a ATM Remote Site B Secondary FIGURE 4 4 Secondary Scoreboard Logging 76 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Rolling Back Updates After a Takeover Rehearsal When the rehearsal completes the Sun SNDR software uses the secondary scoreboard logs to update the appropriate blocks with the current information from the primary volumes the update procedure rolls back the test changes A more complete recovery rehearsal requires that the rehearsal updates be captured and later reflected on the primary server before the workload is swi
45. e resident in host 1 data cache or it might require a secondary disk access If so the Sun SNDR software on host 1 requests blocks from the up to date secondary volume on host2 2 The Sun SNDR software on host 2 transmits the cache blocks 2R over the intersite fiber link to a Sun SNDR software region on host 1 with destaging instructions 3 The Sun SNDR software on host1 updates its disk 7 Restart the application on the primary All steps repeat until the entire volume is copied Subsequent reads from Host A are serviced locally from the newly updated disk Reverse synchronization occurs concurrently with pass through reads Site A Primary Remote Site B Secondary Disk Disk Cache HBA HBA Cache Sun _ hosti host2 SNDR clans ie 3 1 2 y I E Replaced Up to date disk ATM secondary disk a 2R Indicates one transmit and one receive fiber used in intersite fiber link FIGURE 4 6 Reverse Full Synchronization Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 81 82 Recovering From a Primary Site Disaster The Sun SNDR software minimizes the effects of a disaster at the primary site by enabling you to keep the secondary storage images updated Although the secondary Sun SNDR software cache contains the latest writes issued on the primary before the disaster that data might not have bee
46. e shost sdev name for a volume set each time you issue a Sun SNDR command instead of specifying the complete primary and secondary host volume and bitmap information for a volume set sndradm e This command sets the bitmap scoreboard to indicate that a full resynchronization between volumes is required and it enables scoreboard logging It also adds the local volume to the Storage Volume SV driver control the bitmap scoreboard volume is also added to the SV driver Syntax sndradm e g io groupname C tag n config file SNDR set 28 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 sndradm E Caution Before using sndradm E ensure that the volumes are already synchronized by means other than the Sun SNDR software for example restoring the volumes from tape or other media If the volumes are not synchronized before this command is used the secondary or target volume will contain inconsistent data This command clears the bitmap scoreboard logging to indicate that the specified volumes are fully synchronized and enables scoreboard logging It also adds the local volume set to the Storage Volume SV driver control the bitmap scoreboard volume is also added to the SV driver Syntax sndradm E g io groupname C tag n config file SNDR set Chapter 3 Sun SNDR Software Commands 29 30 Disabling the Sun SNDR Software Note See also To
47. een logged earlier by the Sun SNDR software m Rollback resynchronization is a form of update synchronization used for disaster recovery rehearsals and other applications where test updates must be reversed Chapter 4 describes the mechanism to use in a given circumstance When multiple volumes require synchronization the Sun SNDR software can perform several of these techniques concurrently 10 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Getting Started Task Summary TABLE 1 2 lists the high level steps and tasks for getting started with the Sun SNDR software TABLE 1 2 Getting Started Task Summary Task See This Section or Chapter 1 Review the Sun SNDR Chapter 2 and Chapter 3 software commands and supporting file requirements Define the primary and secondary sites Select the volumes for the Sun SNDR software operations Enable the Sun SNDR software for the selected volumes Perform the Sun SNDR software copy update and other operations on volumes Check volume status Volume Size Requirements on page 5 One to Many and Multihop Volume Sets on page 6 Enabling the Sun SNDR Software on page 28 Command Option and Parameter Summary on page 20 Full Forward Synchronization Establishing Replicated Images for the First Time on page 64 Chapter 4 for recovery scenarios Displaying Volume Set and I O Group Status on page 41
48. em administration Sun StorEdge Instant Image 3 0 806 7677 System Administrator s Guide TCP IP and Data Communications Administration 805 4003 Guide Configuration Sun StorEdge Network Data Replicator 3 0 806 7550 Configuration Guide Sun Enterprise 10000 InterDomain Network 806 5230 Configuration Guide xviii Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Accessing Sun Documentation Online A broad selection of Sun system documentation is located at http www sun com products n solutions hardware docs A complete set of Solaris documentation and many other titles are located at http docs sun com For the latest version of released storage software documentation go to http www sun com products n solutions hardware docs Software Ordering Sun Documentation Fatbrain com an Internet professional bookstore stocks select product documentation from Sun Microsystems Inc For a list of documents and how to order them visit the Sun Documentation Center on Fatbrain com at http www fatbrain com documentation sun Sun Welcomes Your Comments Sun is interested in improving its documentation and welcomes your comments and suggestions You can email your comments to Sun at docfeedback sun com Please include the Part No 806 7512 10 in the subject line of your email Preface xix xx Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 CHAPTER 1
49. eparator specifying another volume The following two examples specify the same volumes 3 6 7 8 9 10 11 12 14 and 15 r 3 6 7 8 9 12 14 15 r 3 6 12 14 15 Clears the statistics before displaying current statistics Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Example scmadm S Screen Display The statistics display includes the fields described in TABLE 3 7 Type scmadm S M to display the Sun SNDR software specific statistics press the M key to toggle between the Sun SNDR software screens and regular cache statistics after typing the command TABLE 3 7 Fields for Sun SNDR Software Screen Display Field Description primary Specifies the primary partition link status Indicates whether replication is enabled or disabled or indicates the synchronization direction if a synchronization is in progress secondary Specifies the secondary partition dual copy status Indicates current status using the following keywords logging Data is not being replicated and changes are being logged to the scoreboard need rev sync Logging but an earlier reverse synchronization did not finish executing The primary volume might be in an inconsistent state The need rev sync state is cleared following a successful reverse synchronization or by an Instant Image software update to the primary volume which restores an earlier valid snapshot and removes the need to repeat the reverse sy
50. er volume The Instant Image software is best used just before you perform a resynchronization to ensure that a consistent copy of data exists In this case if the resynchronization fails you at least have a copy of known good data that is usable During the resynchronization process of updating the local and remote sites the data on a secondary Sun SNDR volume is temporarily inconsistent with the primary volume The secondary volume cannot be relied on for data recovery Consistency is restored when the resynchronization is complete To ensure data integrity use Instant Image software regularly to create a point in time copy of data at both sites See the Instant Image documentation listed in Related Documentation on page xvili Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 63 Full Forward Synchronization Establishing Replicated Images for the First Time Before using data on the Sun SNDR software replicated volumes ensure that the contents of the local and remote volume sets match All Sun SNDR software synchronization and update operations in this case start from the primary system because you issue the commands from the primary system Existing Primary and Newly Formatted Secondary Volumes If the primary volume has already been updated locally without the Sun SNDR software replication and contains important information you can copy its image to the newly formatted secondary volume The Sun SNDR
51. essary PIT copies before allowing the synchronization to proceed 70 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Restoring Volumes After a Secondary Site Failure The effort required to restore a secondary site to its remote copy state depends on the hardware and software that is replaced or repaired This section describes restoring disk system and intersite links If a volume is not recoverable after a disk failure follow the steps described in this section Restoring a Failed Secondary Volume FIGURE 4 3 shows restoration of a failed secondary disk The process follows the same steps used to establish an initial Sun SNDR software volume set see Full Forward Synchronization Establishing Replicated Images for the First Time on page 64 The concurrent write updates have been omitted from the figure v To Restore a Volume Set at a Remote Site Use this command host1 sndradm m g io groupname C tag n config file SNDR set set name Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 71 Data Flow FIGURE 4 3 shows restoration of a failed secondary disk 1 The Sun SNDR software on host 1 requests disk blocks from the active primary volume The data might already be resident in host 1 data cache or might require a local disk access 2 The Sun SNDR software transmits the data blocks 2R with destaging instructions over the ATM connect
52. et the asynchronous queue 50 stop Sun SNDR operations and start logging 39 Sun SNDR 20 toggle the autosynchronization state 49 update disk cluster tag name 46 I O group 44 Sun SNDR configuration 45 wait for synchronization to complete 38 configuration files format 14 from Version 2 0 15 copy primary to secondary 34 secondary to primary 35 volume to volume 65 D data service defined GL 1 devices source GL 3 target GL 3 disable Sun SNDR 30 disaster recovery rehearsals 74 disk cluster tag name 46 Index 1 disks GL 1 restoring 71 failed primary 78 displaying volume and group names 42 E enable scoreboard logging 28 29 Sun SNDR 28 29 examples scmadm S 53 55 F failed disk restoring primary 78 failures primary site 78 secondary site 71 fiber alternate 73 forward synchronization 34 full synchronization 65 GL 1 H HDA GL 1 health monitor GL 1 Instant Image adding volumes for Sun SNDR use 32 deleting volumes from Sun SNDR use 32 interruptions 66 primary logging 66 resynchronizing after 66 L local mirrors GL 1 log scoreboard GL 2 logging GL 2 secondary 76 start 39 mirrored partitions GL 2 mirroring GL 2 asynchronous GL 1 establishing images 64 local GL 1 synchronous GL 3 monitoring operations 62 multihop volume sets 6 mutual backup 62 GL 2 O one to many volume sets 6 overview 3 P partitions GL 2 mirrored GL 2 pass th
53. ey To F Scroll forward through the display B Scroll backward through the display M Toggle between regular cache statistics and the Sun SNDR software screens T Display the cumulative key cache statistics generated since the last time the counters were reset the z option resets the counters During synchronization operations the Sun SNDR software screen displays m Percentage of the synchronization completed for each volume m Arrows indicating the direction of the synchronization m Status of each volume Syntax usr opt SUNWscm sbin scmadm S M d delay time 1 logfile r range z TABLE 3 6 describes the scmadm S options Chapter 3 Sun SNDR Software Commands 51 52 TABLE 3 6 scmadm S Options Option Description M a delay time 1 logfile r range Displays the Sun SNDR software statistics If scmadm S is invoked without the M option it displays statistics related to the storage device cache Sets the display update time to delay time seconds Writes all screen outputs to the specified logfile Specifies the cache descriptor for one volume or a combination of a single volume an inclusive range of volumes and multiple volumes The default is that all volumes are displayed Specify the range in this format n n n Where n is the numbers of the specified decimal volumes A colon is a separator specifying an inclusive range of volumes A comma is a s
54. f each other that is operations performed on I O group A volume set 1 are independent of operations performed on I O group A volume set 2 If an operation fails on one or more volume sets in an I O group the state of the data on the volumes in the I O group s volume sets is unknown To correct this m Correct any known problems with the failing sets m Reissue the command on the entire I O group or individual volume sets that failed If the operation is successful the I O group and volume set state returns to a normal condition that is the data stored on all replicated volumes is consistent Sun SNDR Commands and Sun Cluster Operations Caution Do not install or use the Sun StorEdge Version 3 0 Core and data services software on servers in a Sun Cluster 3 0 environment The Version 3 0 software is not co existent with the Sun Cluster 3 0 environment The Version 3 0 software is co existent in the Sun Cluster 2 2 environment where it will not interfere with failover The Version 3 0 core and data services software is cluster aware in the Sun Cluster 3 0 Update 1 environment and provides high availability for the Sun StorEdge software You can use the C tag and C tag options described in TABLE 3 2 in a Sun Cluster 3 0 Update 1 environment only If you accidentally use these options in a noncluster environment the Sun SNDR operation does not execute 22 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guid
55. full reverse copy operation from the secondary volume to the primary volume It also enables replication from the primary volume to the secondary volume any new writes to the primary volume are also replicated to the secondary volume Syntax sndradm m r g io groupname C tag n f config file SNDR set set name Note Do not start the primary application such as a database application that writes to the volumes until the full reverse copy operation finishes executing Chapter 3 Sun SNDR Software Commands 35 Starting a Resynchronization Update Between Volumes Note If a synchronization initiated by the sndradm mor sndradm m r commands is interrupted use the sndradm u update command to finish executing the synchronization Use usr opt SUNWscm sbin scmadm S to view the synchronization progress Use the sndradm u command when all of the following cases exist m Replication was stopped by using the sndradm 1 command or the link was interrupted and scoreboard logging was active m The primary volume has the desired contents m You want to overwrite those segments of the secondary volume that are different from the primary as defined in the scoreboard logs m You intend to start replication from the primary to the secondary volume Use the sndradm u r command when all of the following cases exist m Replication was stopped using the sndradm 1 command or the link was interrupted a
56. ge software Use the sndradm R C command in cases where the disk group name or cluster resource tag are not indicated by the volume path name This command does not affect remote volumes and cannot be used in noncluster environments Tip You can also move all volume sets in one cluster tag to another cluster tag Use the command as follows sndradm C tag R C new tag sndradm R C This command enables you to update or reconfigure the current disk group name or cluster resource tag of the local volume in a volume set tag here is defined as the disk group name or cluster resource tag Syntax sndradm R C tag g io groupname C tag n config file SNDR set set name 46 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Resetting the Replication Mode of a Volume Set Use the sndradm R m command to change the replication mode of a volume set Note If the volume set is part of an I O group remove the volume set from the group and change its mode You can remove one volume set selected volume sets or all volume sets from a group using the sndradm R g command See Moving a Volume Set to a Different I O Group on page 44 and the procedure described in To Remove a Volume Set from a Group and Change Its Replication Mode on page 48 sndradm R m This command enables you to reconfigure the replication or mirroring mode of a volume set Syntax sndr
57. gement system DBMS logs m Access control files You can enable these volumes for remote copy individually as part of a volume set or collectively as part of an I O group as described in Chapter 3 You can exclude volumes from the Sun SNDR software configuration if they can be reconstructed at the recovery site or if they seldom change m Temporary volumes such as those used in sort operations m Spool files m Paging volumes Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 61 Using the Storage Volume Interface When you enable volume sets using the usr opt SUNWesm sbin sndradm command you place the specified volumes under control of the Storage Volume SV driver See Enabling the Sun SNDR Software on page 28 You can also manually place volumes under SV control through a command line interface named svadm For example you can add the volumes as follows usr opt SUNWesm sbin svadm e f config file where config file is an ASCII file listing the volume the full path to the raw device node You can also add individual volumes from the command line See the svadm man page it also describes the format of a configuration file Monitoring Sun SNDR Software Operations Use the usr opt SUNWscm sbin scmadm S command described in the section Getting Sun SNDR Software and Storage Cache Statistics The scmadm Command on page 51 to monitor the progress of the Sun SNDR software operations
58. his Feature Enables You To Optimized resynchronization RAID support Security and Internet Protocols Version 3 0 Stop and start control of remote replication on a logical volume basis Sun StorEdge Instant Image software integration Synchronous and asynchronous volume replication between physically separate sites Cluster capability Resynchronize volumes following disk link system and storage platform outages you only replicate those blocks that were modified Use RAID volumes as part of your Sun SNDR software strategy Volumes can be any RAID level Use Version 3 0 securely and efficiently in the Sun Solaris 7 and 8 operating environments which support Internet Security Protocol IPsec The Solaris 8 operating environment also supports Internet Protocol Version 6 IPv6 The Solaris 7 operating environment does not support IPv6 Version 3 0 does not require the use of an rhosts file You place the hosts to be used in the etc hosts file of each host running the Sun SNDR Version 3 0 software in your configuration Have fine control over replication at the logical volume level Make point in time volume copies of your data for additional point in time coordination and recovery Plan for disaster recovery and business continuance using physically separate primary and secondary sites The Sun SNDR software design is link neutral meaning that it can use any Sun network adapter that supports TC
59. ication activity was high prior to the rehearsal m Declare the secondary volumes available for access from the recovery hosts m Start application level recovery procedures to ensure a consistent starting point for future transactions During a read operation from the secondary recovery copy m The secondary remote site host issues a read request on host 2 against the recovery copy m Asthe read request returns a cache miss the appropriate blocks are read from the replicated copy volume into host 2 data cache m The read operation results are returned to the secondary remote site host Subsequent host reads and writes populate the recovery system data cache and normal local access is restored 74 SunStorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Secondary Updates During a Takeover Rehearsal During the rehearsal you can apply test updates from a secondary host to the secondary volumes to evaluate the recovery mechanisms If these test updates are not part of the permanent business record they must be undone when the recovery copy is returned to its secondary Sun SNDR software role See To Perform a Secondary Rollback on page 77 for the appropriate procedures Scoreboard logs track the test updates occurring on the secondary volumes during recovery rehearsals Data Flow FIGURE 4 4 shows secondary write logging during rehearsals described as follows 1 The remote site host issues a writ
60. ion to a Sun SNDR software region on remote host2 3 The Sun SNDR software on host 2 updates its remote volume and acknowledges the action to host1 All steps repeat until the entire volume is copied Use scmadm S M to monitor the restoration process Site A Primary Remote Site B Secondary Disk Disk HBA Cache Cache HBA host2 host ____ Sun el ia i SNDA 3 v M Newly replaced 2R 24 Active primary remote disk disk ATM I os 2R Indicates one transmit and one receive fiber used in intersite fiber link FIGURE 4 3 Restoring a Failed Secondary Volume Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Restoring a Failed Secondary Server Restoring a failed secondary server might involve both updating and fully resynchronizing the secondary disks depending on the severity and duration of the failure The update operation updates any secondary volumes whose contents were maintained during the failure The full synchronization operation writes a complete copy of the primary volumes to volumes residing on secondary disks that were replaced or whose state is unknown To Perform an Update Operation Use this command hostl sndradm u g io groupname C tag n f config file SNDR set set name To Perform a Full Synchronization Use this command host1 sndradm m g i
61. it would be entered in a config file phost pdev pbitmap shost sdev sbitmap ip sync l async Syntax sndradm i g io groupname C tag Use the g io groupname and C tag options to filter the output so that it includes only those volumes that are part of io groupname or tag 42 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Displaying Link Status Use the sndradm H command to check the status of the link connecting primary and secondary hosts Note Use the ping 1M command to supplement the link status shown by sndradm H sndradm H This command displays the currently configured primary and secondary host machine names volumes and bitmap volumes for the selected sets It also shows whether the link between machines is active or inactive For example sndradm H atm fred dev vx rdsk freddg sndr_vol01 Report SNDR link health Y N N y SNDR atm ethel dev rdsk c3t9d0s3 dev rdsk c6t0d0s4 atm fred dev vx rdsk freddg sndr_vo101 dev rdsk c6t0d0s6 Inactive Active indicates that replication or synchronization operations are occurring on the link used by the specified volume set Inactive indicates that the link might be down or that all sets are in logging mode Syntax sndradm H shost sdev where shost is the secondary host name and sdev is the secondary volume partition name separated by a colon When you first enable a set the Sun SNDR software
62. k Cache HBA HBA Cache Sun __ hosti host2 SNDR lsrR 5 4 I 2 y ig y i score score board a board 7 Stale Up to date V3 a 4 local disk ATM secondary disk ae e e i SZ _ a 1R 3R Indicates one transmit Copy of secondary and one receive fiber scoreboard used in intersite fiber link FIGURE 4 7 Reverse Update Synchronization Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Full Reverse Synchronization Completely Restoring a Primary Site From the Secondary Site If the primary server becomes inoperative and primary data on the primary disks is lost update logs at the secondary systems have little value You must perform a reverse full synchronization on the repaired or replaced primary host In other words volume to volume copies from the secondary to the primary are required for all Sun SNDR software managed volumes This reverse synchronization process ensures that only the latest data is deposited on the primary disks To Perform a Full Reverse Synchronization On the primary host use this command hostl sndradm m r g io groupname C tag n config file SNDR set set name FIGURE 4 8 shows this restoration process for the primary storage platform The procedure is similar to that of restoring a single primary disk see Example To Restore a Failed Primary Vol
63. m memory that keeps the cache statistics Memory Usage data CODE EXAMPLE 3 2 Sample scmadm S Display Cache Statistics SAMPLE 9 FERRER Storage Cache ERETTE 14 43 44 disk_io cache write blocks cd cached_partition reads writes reads writesdirty todisk failed 0 k c0t115d0s3 2559 0 0 0 0 0 0 1 k c0t116d0s3 3071 0 0 0 0 0 0 2 k c0t117d0s3 2559 0 0 0 0 0 0 3 sk c0t98d0s3 0 0 0 0 0 0 0 4 sk c0t98d0s1 0 0 0 0 0 0 0 5 sk c0t98d0s5 0 0 0 0 0 0 0 6 sk c0t96d0s3 0 0 0 0 0 0 0 Kbytes s total 8189 0 0 0 accesses s read s write s Sreadh Swriteh misses s misses s 16 00 0 00 0 00 0 0 0 0 16 00 0 00 CODE EXAMPLE 3 3 Sample scmadm s Display Cumulative Cache Statistics SAMPLE 10 ARAL Storage Cache Cumulative RETTE 14 43 44 disk_io cache cd cached_partition reads writes reads writes 0 k c0t115d0s3 2034688 0 0 0 1 k c0t116d0s3 2031104 0 0 0 56 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 2 k c0t117d0s3 2028032 0 0 0 3 sk c0t98d0s3 9 10 4 0 4 sk c0Ot98d0s1 9 10 4 0 5 sk c0t98d0s5 9 10 4 0 6 sk c0t96d0s3 0 0 0 0 Kbytes total 6093851 30 12 0 accesses read write Sreadh writeh misses misses 11950 27 0 O2 0 0 11908 15 cachesize blocksize 65536K 8192 Write blocks available Net 0 4096 Net 1 0 Net 2 0 Net 3 0 LRU stats Blocks Requeued Optimized 8192 0 0 Total Cache Memory Usage 2320 Kbytes
64. n SNDR Software Commands software on servers in a Sun Cluster 3 0 environment The Version 3 0 software is not co existent with the Sun Cluster 3 0 environment The Version 3 0 software is co existent in the Sun Cluster 2 2 environment where it will not interfere with failover The Version 3 0 core and data services software is cluster aware in the Sun Cluster 3 0 Update 1 environment and provides high availability for the Sun StorEdge software 1 Caution Do not install or use the Sun StorEdge Version 3 0 Core and data services Note To use the Sun SNDR software you must be the root user This chapter describes the Sun SNDR commands available from the command line using usr opt SUNWesm sbin sndradm Chapter 4 describes how to use the command in various data recovery scenarios The topics in this chapter include m Command Option and Parameter Summary on page 20 m Enabling the Sun SNDR Software on page 28 m Disabling the Sun SNDR Software on page 30 m Adding and Deleting Instant Image Software Volumes on page 32 m Starting a Full Synchronization Copy Between Volumes on page 34 m Starting a Resynchronization Update Between Volumes on page 36 m Waiting for Synchronization to Finish Executing on page 38 m Stopping Sun SNDR Software Operations and Starting Logging on page 39 m Assigning a New Scoreboard Bitmap to a Volume Set on page 40 m Displaying Volume
65. n destaged to the secondary disks yet After detecting an interruption in the Sun SNDR software service the Sun SNDR software automatically destages the secondary Sun SNDR software cache to its corresponding secondary volumes After all the secondary volumes have been updated with the latest Sun SNDR software cache images the secondary volumes can be accessed by the secondary hosts The scmadm S screen displays confirm that destaging is complete Run application level recovery procedures to ensure a well known state at the secondary site The workload can then be switched to the secondary hosts for continued business operation Until the extent of the primary failure is understood keep the Sun SNDR software enabled at the secondary site to track disk areas that are being modified Under some confined disasters the secondary update logs speed primary restoration as described in Full Reverse Synchronization Completely Restoring a Primary Site From the Secondary Site on page 85 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Reverse Synchronization Updating the Primary Site From the Secondary Site The primary volume state can be frozen as host workloads are switched to the secondary site This is true in more realistic disaster rehearsals and might be true in confined disasters Under these conditions the secondary site activates its Sun SNDR software scoreboard logs to track changes not yet seen
66. nchronization to restore consistency need sync Logging but an earlier synchronization did not finish executing The secondary volume might be in an inconsistent state The need sync state is cleared following a successful synchronization or by an Instant Image software update to the secondary volume which restores an earlier valid snapshot and removes the need to repeat the synchronization to restore consistency replicating Data written to the primary is being replicated to the secondary Formerly called enabled rev sync A synchronization from secondary to primary is under way sync A synchronization from primary to secondary is under way volume down The volume has failed recovery needed Displays the percentage of segments of the partition that require recovery recovery Displays the percentage of the partition that has been completed resynchronized Chapter 3 Sun SNDR Software Commands 53 See CODE EXAMPLE 3 1 for a sample output m The equals sign in the link status field indicates that the link is up and replication is enabled m The asterisks in the recovery fields are graphical representations of the percentage of recovery needed and completed m The arrows gt indicate the synchronization direction CODE EXAMPLE 3 1 scmadm S Link Status Display SAMPLE 109056 EXX Dual Copy StatiSstros X FEAX 17 40 10 primary link status secondary dual copy status ma dsk c
67. nchronous mirroring is limited to short distances tens of kilometers because of the detrimental effect of propagation delay on I O response times Simulation of a switchover to the secondary system after a staged failure of the primary system Device receiving the remote copy The resynchronization operation that copies only the blocks modified since a Sun SNDR software interruption as identified by scoreboard logging reducing the time to restore remotely mirrored sets See disk The specification that specifies the complete Sun SNDR software volume configuration information primary and secondary hosts volume partitions scoreboard log bitmaps and replication mode asynchronous or synchronous Glossary 3 Glossary 4 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Index A alternate fiber 73 assign a new scoreboard bitmap 40 asynchronous mirroring GL 1 queue 50 autosynchronization state 49 B bitmaps 16 C cluster operations 7 22 commands assign a new scoreboard bitmap 40 compatibility with Version 2 0 7 copy primary to secondary 34 copy secondary to primary 35 disable 30 display link status 43 status brief 41 status detailed 41 volume and group name list 42 enable scoreboard logging 28 29 Sun SNDR 28 29 refresh primary from secondary 36 37 refresh secondary from primary 36 resetting the replication mode of a volume set 47 scmadm S 51 s
68. nd scoreboard logging was active m The secondary volume has the desired contents m You want to overwrite those segments of the primary volume that are different from the secondary as defined in the scoreboard logs m You intend to start replication from the primary to the secondary volume sndradm u This command resynchronizes the secondary volume from the primary volume It updates the secondary volume according to the changes based on scoreboard logs maintained while replication was stopped It also enables concurrent replication between the primary and secondary volumes any new write operations to the primary volumes are also replicated to the secondary volumes Syntax sndradm u g io groupname C tag n config file SNDR set set name 36 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 sndradm u r Tip You can use this command to roll back volume changes on the primary volume to a point in time image captured on the stopped secondary volume This command resynchronizes the primary volume from the secondary volume It updates the primary volume according to the changes based on scoreboard logs maintained while replication was stopped It also enables concurrent replication between the primary volume and secondary volumes any new write operations to the primary are also replicated to the secondary volumes Syntax sndradm u r g io groupname C tag n
69. nd version sndradm h Results from entering this information from the command prompt command at the command sndradm v prompt Display the Sun SNDR software status sndradm p Displaying Volume Set and I O Group Status on page 41 sndradm P Display the Sun SNDR software volume set and I O sndradm i Displaying a List of Current group names Volume Sets and Group Names on page 42 Display the status of the link connecting systems sndradm H Displaying Link Status on running the Sun SNDR software page 43 Chapter 3 Sun SNDR Software Commands 25 TABLE 3 3 Sun SNDR Software Tasks and Related Command Parameters Continued Operation Command For Detailed Information See Change the scoreboard bitmap of a volume set Reset the replication mode of a volume set Set the asynchronous queue Stop the Sun SNDR software replication and log scoreboards Toggle the autosynchronization state Move all the specified SNDR sets to a different group Update or reconfigure the Sun SNDR software volume sets Update or reconfigure the disk group name or cluster resource tag sndradm R b sndradm R m sync async sndradm W sndradm F sndradm 1 sndradm a on off sndradm R g sndradm R f config file sndradm R C Assigning a New Scoreboard Bitmap to a Volume Set on page 40 Resetting the Replication Mode of a Volume Set on page 47 Setting the Asynchro
70. nd versions differ The Version 3 0 command provides more options and capabilities such as the ability to operate on groups of volume sets Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 TABLE 3 1 rdcadm and sndradm Command Differences Between Sun SNDR Software Version 2 0 and Version 3 0 Sun SNDR Software Version 2 0 Sun SNDR Software Version 3 0 Difference rdcadm all options rdcadm a value rdcadm A sndradmand rdcadm all options sndradm a on off sndradm P When you use any option and you do not specify a SNDR set Version 2 0 operates on all SNDR sets in the rdc cf file or those as specified by f config file Version 3 0 operates on all enabled SNDR sets or those as specified by f config file Version 2 0 value is 0 off or 1 on Version 3 0 specify on or off instead of Oorl Version 2 0 shows the autosynchronization state Version 3 0 shows detailed information about all SNDR sets Chapter 3 Sun SNDR Software Commands 21 Sun SNDR Commands and I O Group Operations Adding the Sun SNDR software volume sets to an I O group enables you to issue a single command that operates on all volume sets in the specified I O group or groups excluding all other volumes sets from the operations Most commands allow for group operations and perform them when you include g io groupname in the command syntax The operations performed are independent o
71. not required Software on page 28 Enable the Sun SNDR software for the specified set sndradm e Enabling the Sun SNDR sync required Software on page 28 Disable the Sun SNDR software for the specified set sndradm d Disabling the Sun SNDR Software on page 30 Add or delete a Sun StorEdge Instant Image software sndradm I Adding and Deleting Instant volume group for use with the Sun SNDR software Image Software Volumes on page 32 Copy the entire contents of the primary volume to the sndradm m Starting a Full secondary volume also known as full synchronization Synchronization Copy Between Volumes on page 34 Copy the entire contents of the secondary volume to sndradm m r Starting a Full the primary volume also known as full reverse Synchronization Copy synchronization Between Volumes on page 34 Update only the changed data of the primary volume sndradm u Starting a Resynchronization to the secondary volume also known as update Update Between Volumes on synchronization or resynchronization page 36 Update only the changed data of the secondary sndradm u r Starting a Resynchronization volume to the primary volume also known as reverse Update Between Volumes on synchronization or reverse update page 36 Wait for a synchronization operation to finish sndradm w Waiting for Synchronization executing to Finish Executing on page 38 Display the Sun SNDR command syntax a
72. nous Queue on page 50 Stopping Sun SNDR Software Operations and Starting Logging on page 39 Toggling the Sun SNDR Software Autosynchronization State on page 49 Moving a Volume Set to a Different I O Group on page 44 Updating the Volume Set Configuration on page 45 Updating the Disk Cluster Tag Name on page 46 26 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Which Host Do I Issue Commands From Certain commands and synchronization situations require you to issue a command from a primary host secondary host or both See TABLE 3 4 TABLE 3 4 Which Host to Issue Commands From Task Where Command Is Issued Comments Assign a new bitmap to a volume set Disable the Sun SNDR software Enable the Sun SNDR software Full forward or reverse synchronization copy Forward or reverse synchronization update Log Toggle the autosynchronization state Update an I O group Primary and secondary host Primary or secondary host Primary and secondary host Primary and secondary host Primary host Primary host Primary host Primary or secondary host Primary Primary and secondary Perform this command first on the host where the new bitmap resides and is being assigned and then perform it on the other host You can disable on one host leave the other host enabled and then re enable the disabled host
73. nowledges the update to the primary system Site A Primary Remote Site B Secondary Disk Cache HBA C lt I ani Disk HBA Cache host2 hosti f sun i SNDR v oi s L Local Remote FIGURE 4 1 Indicates one transmit and one receive fiber used in intersite fiber link Full Synchronization Volume to Volume Copy Using ATM Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 65 Handling Interruptions The Sun SNDR software uses a periodic intersite signal to monitor the health of primary and secondary systems The absence of a health monitor signal indicates an interruption in the Sun SNDR software service A failure or impairment in the intersite link or an outage at the remote site can cause interruptions You can introduce interruptions intentionally to exercise remote failure strategies for example during the disaster recovery rehearsals described in Rehearsing Disaster Recovery on page 74 Primary Logging During Interruptions During interruptions the Sun SNDR software tracks primary volume areas that are being updated locally but have not yet been copied to the secondary site Under several circumstances when the Sun SNDR software service is restored update resynchronization can be requested automatically or manually using the scoreboard logging information to update the remote site Forward Res
74. o an existing volume set You can change the bitmaps on the primary or secondary host This command copies any data from the old bitmap to the new bitmap Syntax sndradm R b p s new bitmap name g io groupname C tag n config file ISNDR set set name m To change a primary host bitmap issue the command from the primary host m To change a secondary host bitmap issue the command from the secondary host m Optionally to ensure consistency for status reporting issue the command from both hosts For example to change a secondary host bitmap issue the command from the secondary host first and then issue it from the primary host 40 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Displaying Volume Set and I O Group Status Use the sndradm p and sndradm P commands to display status information Use the g io groupname and C tag options to filter the output so that it includes only those volumes that are part of io groupname or tag sndradm p This command displays a brief version of the Sun SNDR software status for volume sets and I O groups The following is an example of output of this command on the primary host sndradm p dev rdsk c4t96d0s1 lt fast7 dev rdsk c2t0d0s1 dev rask c4t97d0s1 lt fast7 dev rdsk c2t0d0s1 dev rdsk c4t98d0s1 lt fast7 dev rdsk c2t0d0s1 Syntax sndradm p g io groupname C tag sndradm P This command dis
75. o groupname C tag n config file SNDR set set name Switching to an Alternate Fiber ATM Only Most intersite link impairments are temporary but a fiber cable can be accidentally cut Fiber plant suppliers support separately routed links between the two sites for added protection They might use an automatic switch or might need to manually switch fiber cable pairs at a patch panel to redirect the signal to the alternate route Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 73 Rehearsing Disaster Recovery The Sun SNDR software enables you to perform disaster rehearsals easily which encourages frequent verification of disaster preparedness Validating contingency procedures through rehearsals is an important aspect of any disaster recovery plan Perform rehearsals regularly and refine them whenever a significant change is made to the primary or secondary processing environments Rehearsing Recovery From Secondary Volumes You can simulate a disaster by temporarily interrupting the Sun SNDR software network connection and practicing takeover on the secondary site To do this with the Sun SNDR software break the network connection between the primary and secondary sites Complete these steps before proceeding with recovery m Use scmadm S M to verify that all Sun SNDR software secondary volume updates have been destaged to disk Destaging might be in progress if the Sun SNDR software repl
76. olume set consists of a primary volume residing on a local host and secondary volume residing on a remote host The volume set also includes a bitmap volume on each host to track write operations and differences between the volumes The Sun SNDR software enables you to group volume sets You can assign specific volume sets to a group to perform replication on these volume sets and not on others you have configured Grouping volume sets also guarantees write ordering write operations to the secondary volume occur in the same order as the write operations to the primary volume You can also group volume sets according to their cluster or resource tag to perform replication in a clustered environment The Sun SNDR Version 3 0 software is m Co existent in the Sun Cluster 2 2 environment It will not interfere with failover m Not co existent with the Sun Cluster 3 0 environment m Cluster aware in the Sun Cluster 3 0 Update 1 environment and provides high availability for the Sun StorEdge software See Using the Sun StorEdge Data Services Software in a Sun Cluster Environment on page 7 You can update the data on the secondary volume by issuing a command to resynchronize the volumes You can also restore data from the secondary volume to the primary volume by issuing a command to reverse resynchronize the volumes The secondary volumes can be updated synchronously in real time or asynchronously using a store and forward technique Typically
77. omates update resynchronization after a network link or machine failure if the Sun StorEdge Instant Image software is also installed and you have added Instant Image software volume groups to the data service it invokes point in time copies when necessary to protect the data volumes being updated during a resynchronization When a network link being used by the Sun SNDR software becomes unavailable the daemon attempts to invoke the Sun SNDR software update commands to resynchronize all volume sets that have autosynchronization enabled and are using the network link The daemon is also notified when any Sun SNDR software resynchronization starts or finishes executing The daemon performs Instant Image software point in time copy operations on the secondary or target host if configured On a secondary host the daemon checks whether a file system is currently mounted on the secondary volume and informs the kernel not to allow the synchronization to start if the file system is currently mounted Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 69 Use the sndradm I command to create data service configuration entries marked with the ndr_ii key The ndr_ii entries contain an additional state field that the kernel uses to determine when point in time PIT copies must be made The kernel notifies the Sun SNDR software synchronization daemon on the target system whenever a sync is started and waits for sndrsyncd to perform any nec
78. ore information about this configuration file format TABLE 2 1 Optional Configuration File Format Fields Primary Host Server on which the primary volume resides Primary Device Primary volume partition to be copied Specify full path names only for example dev dsk c0t1d02s4 Primary Bitmap Volume partition in which the bitmap scoreboard logs of the primary partition is stored Specify full path names only Secondary Host Server on which the secondary volume resides Secondary Device Primary volume partition to be copied Specify full path names only Secondary Bitmap Volume partition in which the bitmap scoreboard logs of the secondary partition is stored Specify full path names only Protocol Network transfer protocol Specify ip Mode syncl async Sun SNDR software operating mode sync is the mode where the I O operation is confirmed as complete only when the remote volume has been updated async is the mode where the primary host I O operation is confirmed as complete before updating the remote volume Options g io groupname C tag An I O group name can be specified using the g character When running in a Sun Cluster Version 3 0 Update 1 environment a cluster resource group tag can be specified using the C character 14 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Configuration Files from Version 2 0 If you upgrade from Sun SNDR software Version 2 0 to Version 3 0
79. patible with the Sun SNDR software Version 2 0 rdcadm CLI The Version 3 0 sndradm command is also linked to the rdcadm command so that if your existing scripts reference the rdcadm command the Version 3 0 software will use the sndradm command to perform the specified operations See TABLE 3 1 on page 21 There are two ways to use the CLI to execute commands m As part of an existing or new script file m From the Solaris operating environment root user prompt Using the Sun StorEdge Data Services Software in a Sun Cluster Environment Caution Do not install or use the Sun StorEdge Version 3 0 Core and data services software on servers in a Sun Cluster 3 0 environment The Version 3 0 software is not co existent with the Sun Cluster 3 0 environment The Version 3 0 software is co existent in the Sun Cluster 2 2 environment where it will not interfere with failover The Version 3 0 core and data services software is cluster aware in the Sun Cluster 3 0 Update 1 environment and provides high availability for the Sun StorEdge software You can use the C tag and C tag sndradm command options described in Chapter 3 in a Sun Cluster 3 0 Update 1 environment only If you accidentally use these options in a noncluster environment the specified Sun SNDR operation does not execute You cannot use the Sun StorEdge Fast Write Cache FWC product including the SUNWnvm Version 3 0 software in a Sun Cluster environment because cached data is
80. plays a detailed version of the Sun SNDR software status for volume sets and I O groups The following is an example of output of this command on the primary host sndradm P dev rdsk c4t96d0s1 lt autosync off dev rdsk c4t97d0s1 lt autosync off dev rdsk c4t98d0s1 lt autosync off max q writes max q writes max q writes fast7 dev rdsk c2t0d0s1 60 max q fbas 800 mode sync fast7 dev rdsk c2t0d0s1 60 max q fbas 800 mode sync fast7 dev rdsk c2t0d0s1 60 max q fbas 800 mode async Syntax sndradm P g io groupname C tag Chapter 3 Sun SNDR Software Commands 41 Displaying a List of Current Volume Sets and Group Names Use the sndradm i command to display volume set and I O group names Tip You can also use the output of this command to create a configuration file suitable for editing and using with the sndradm R config file command sndradm i This command enables you to display a list of the current volume set and I O group names in use The following is an example of the output sndradm i fast7 dev rdsk c2t0d0s1 dev rdsk c2t1d0s0 fast8 dev rdsk c4t96d0s1 dev rdsk c6t0d0s4 ip sync fast7 dev rdsk c2t0d0s1 dev rdsk c2t1d0s3 fast8 dev rdsk c4t97d0s1 dev rdsk c6t0d0s6 ip sync fast7 dev rdsk c2t0d0s1 dev rdsk c2t1d0s4 fast8 dev rdsk c4t98d0s1 dev rdsk c6t0d0s8 ip async Note that the output is formatted as
81. re operations Control the Sun SNDR software volume sets simultaneously by grouping them This feature is essential in installations requiring you to maintain consistent contents of a group of volumes A group is a collection of Sun SNDR software sets that have the same group name primary and secondary interfaces and mirroring mode Mixed groups those where mirroring modes are asynchronous for one set and synchronous for another set are not allowed The Sun SNDR software maintains write ordering for volumes in a group to ensure that the data on the secondary volumes is a consistent copy of the corresponding primary volumes Replicate data from one primary volume to a secondary volume the secondary volume then replicates the data again to another secondary volume and so on in a daisy chain fashion See One to Many and Multihop Volume Sets on page 6 Concurrently transmit and receive remote dual copies to and from its remote counterpart Also known as a bilateral relationship Replicate data from one primary volume to many secondary volumes residing on one or more hosts When you perform a forward resynchronization you can synchronize one volume set or all volume sets Issue a separate command for each set You can also update the primary volume using a specific secondary volume See One to Many and Multihop Volume Sets on page 6 Chapter 1 Overview 3 4 TABLE 1 1 Sun SNDR Software Features Continued T
82. rough reads 79 primary GL 2 disk restoring failed 80 site disaster recovery 82 site failures 78 updating site 83 R RAID GL 2 reads pass through 79 recovery primary site disaster 82 refreshing primary from secondary 36 37 secondary from primary 36 rehearsals disaster recovery 74 Index 2 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 recovery from secondary volumes 74 rolling back updates 77 secondary updates 75 takeover GL 3 reset the volume set replication mode 47 restoring failed primary disk 78 primary from secondary 36 primary from secondary complete 85 secondary disk 71 resynchronization forward and reverse update 36 37 reverse full synchronization 81 update synchronization 83 rollback synchronization GL 2 rolling back updates 77 rolling disaster GL 2 S scmadm S example 53 55 options 52 scoreboard log GL 2 secondary GL 3 logging 76 restoring primary from 85 site failures 71 updates during rehearsal 75 source device GL 3 start logging 39 status displaying 41 stop Sun SNDR operations and start logging 39 Sun StorEdge Instant Image see Instant Image 32 synchronization operations 83 GL 3 forward 34 full 65 GL 1 reverse full 81 rollback GL 2 update 36 68 GL 3 synchronous mirroring GL 3 T takeover rehearsal GL 3 target device GL 3 terminology asynchronous mirroring GL 1 full synchronization GL 1 mutual back
83. s spread over a period of hours that might impair multiple components in a Sun SNDR software configuration A special bitmap that tracks writes to a volume rather than providing a running log of each I O event Scoreboard logging is a method for tracking volume updates that have not been remotely copied while the remote service is interrupted or impaired The blocks that no longer match their remote sets are identified for each source volume The Sun SNDR software uses this scoreboard log to re establish a remote mirror through an optimized update synchronization rather than through a complete volume to volume copy Glossary 2 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 secondary source device Sun SNDR software Sun SNDR software log synchronization synchronous mirroring takeover rehearsal target device update resynchronization volume volume set The remote counterpart of a primary system or volume where copies are destined Remote copies are transmitted without host intervention between peer servers A server might act as primary storage for some volumes and secondary remote storage for others A device used as the originating device in the remote copy Sun StorEdge Network Data Replicator software See scoreboard log The process of establishing an identical copy of a source volume onto a target volume as a precondition to Sun SNDR software mirroring The process of sy
84. s unknown because of system or disk failure you might need to make full volume copies to reestablish matching Sun SNDR software volume sets In this case use the sndradm m command to fully update the secondary volume set Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 67 Site A Primary Data Flow FIGURE 4 2 shows an update resynchronization using an ATM link from the primary system to its secondary system when the secondary volumes are stale from the interruption 1 5 The Sun SNDR software on host1 examines a scoreboard from the primary and secondary hosts for the Sun SNDR software managed volumes affected by the interruption The Sun SNDR software on host1 requests the blocks that were updated during the interruption from the up to date volume The data might already reside in the host1 data cache or on the local disk The Sun SNDR software on host1 transmits the update blocks 3R to host 2 Sun SNDR software using the SunATM connection The Sun SNDR software on host2 refreshes its stale replicated image with the updated blocks and acknowledges the action to host1 The Sun SNDR software revises the scoreboard to track the remote update All steps repeat until the remote replicated image is up to date Use scmadm S M to monitor the resynchronization progress Remote Site B Secondary Disk Disk Cache HBA HBA Cache host1 host2 Sun j R 2 ulese I SNDR
85. sing Recovery From Secondary Volumes 74 Secondary Updates During a Takeover Rehearsal 75 Data Flow 75 Rolling Back Updates After a Takeover Rehearsal 77 v To Perform a Secondary Rollback 77 Primary Site Failures 78 Failed Primary Disk 78 Data Flow 79 v Example To Restore a Failed Primary Volume 80 Recovering From a Primary Site Disaster 82 Reverse Synchronization Updating the Primary Site From the Secondary Site 83 v To Start the Reverse Synchronization From the Secondary to the Primary Volumes 83 Data Flow 84 Full Reverse Synchronization Completely Restoring a Primary Site From the Secondary Site 85 v To Perform a Full Reverse Synchronization 85 Disabling Remote Replication 86 v To Permanently Terminate the Sun SNDR Software Remote Replication and Resynchronization Services 87 Glossary GL 1 Contents vii viii Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Figures FIGURE 1 1 FIGURE 4 1 FIGURE 4 2 FIGURE 4 3 FIGURE 4 4 FIGURE 4 5 FIGURE 4 6 FIGURE 4 7 FIGURE 4 8 One to Many and Multihop Volume Sets 6 Full Synchronization Volume to Volume Copy Using ATM 65 Update Synchronization of a Secondary Volume Set 68 Restoring a Failed Secondary Volume 72 Secondary Scoreboard Logging 76 Pass Through Reads to Bypass Local Disk Failure 79 Reverse Full Synchronization 81 Reverse Update Synchronization 84 Restoring the Primary Site from the Secondary Site 86 x Sun
86. so you might accidentally remove enabled volumes using the Sun StorEdge SV driver svadm d command The svadm command currently has no checking in place to prevent a configured volume from being removed from an active Sun SNDR volume set To remove a volume ensure that it is not configured by using the sndradm i command options to display volume information If the volumes are not listed they can be safely removed 1 Disable the volumes in the Sun StorEdge software by using the sndradm d command 2 Remove the volumes from SV control using the svadm d command Chapter 3 Sun SNDR Software Commands 31 Adding and Deleting Instant Image Software Volumes Use the sndradm I command to add or delete Instant Image software volumes for use with enabled Sun SNDR software volume sets You can use this command on the secondary and primary hosts to offer data protection during reverse and forward synchronization update operations You also use this command to offer data protection during an automatic resynchronization see Autosynchronization With Instant Image Software Configured on page 69 Note Use the sndradm e command to enable Sun SNDR software volume sets first before using this command Enabling the Sun SNDR Software on page 28 describes this command sndradm I a This command adds an Instant Image volume group entry to the data services in a format similar to that of the rdc_ii cf file used with the Sun
87. software performs this initial primary volume to secondary volume copy while also forwarding new online updates to the secondary volume v To Fully Synchronize Specific Remote Volumes While Applying New Updates Use this command host1 sndradm m g io groupname C tag n config file SNDR set set name FIGURE 4 1 shows the full resynchronization process using an ATM link This process also enables simultaneous write updates from the local to remote volumes Note The illustrations in this section show the network link type as ATM Although the Sun SNDR software is most likely to be used with SunATM link level interfaces the Sun SNDR software can be used with any Sun supported link level interface that is TCP IP capable such as Gigabit Ethernet Gigabit Ethernet Fibre Channel and others 64 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 Data Flow FIGURE 4 1 shows the full resynchronization process using an ATM link 1 The Sun SNDR software on the primary system host 1 requests disk blocks from the active primary volume The data might already be resident in the primary system data cache or might require a local disk access 2 The Sun SNDR software transmits the disk blocks with destaging instructions over the ATM connection to a cache region on the secondary system 3 The Sun SNDR software on the secondary system updates its remote volume and ack
88. t converts them for use with Version 3 0 Chapter 2 Configuration Files and Bitmaps 15 Bitmaps Note After editing the usr kernel drv rdc conf file reboot your server The Sun SNDR software uses regular raw devices to store bitmaps These raw devices should be stored on a disk separate from the disk that contains the data Configure RAID such as mirrored partitions for these bitmap devices and ensure that the mirrored members are not stored on the same disk as the data In a clustered environment a bitmap must reside only on a volume The bitmap volume in this case must be part of the same disk group or cluster resource group as the corresponding primary or secondary data volume A bitmap maintained on disk might persist across a system crash depending on the setting of rdc_bitmap_mode in usr kernel drv rdc conf For example rdc_bitmap_mode Sets the mode of the RDC bitmap operation acceptable values ar 0 autodetect bitmap mode depending on the state of SDBC default 1 force bitmap writes for every write operation so an update resync can be performed after a crash or reboot 2 only write the bitmap on shutdown so a full resync is required after a crash but an update resync is required after a reboot rdc_bitmap_mode 0 If your server is configured in a clustered environment set the bitmap mode to 1 If your server is not configured in a clustered environment you can
89. tched back See Reverse Synchronization Updating the Primary Site From the Secondary Site on page 83 for more detail v To Perform a Secondary Rollback On the primary host use this command host1 sndradm u g io groupname C tag n config file SNDR set set name Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 77 Primary Site Failures This section contains information needed for handling primary site failures Failed Primary Disk The Sun SNDR software provides continuous data access during primary volume failures The Sun SNDR software high availability features are a superset of RAID 1 and RAID 5 storage protection that can be optionally configured for the primary volumes The Sun SNDR software remote volume access features start only after the disk protection schemes on the primary system are unable to provide data access to the local devices In the linear and striped RAID 0 cases failure of a single disk storing the primary volume triggers the Sun SNDR software to transparently redirect disk reads and writes to the remote storage system If the primary logical volume is locally mirrored RAID 1 across two physical disks on the same system a single disk failure results in its local mirror disk handling all requests for cache staging on a read miss and cache destaging The Sun SNDR software relies on the remote site secondary devices only if both local mirrors fail
90. tions necessary to preserve a valid point in time copy of the data on the secondary system before starting a Sun SNDR software synchronization to update the secondary You can configure Sun StorEdge Instant Image volume groups for use with the Sun SNDR software See Adding and Deleting Instant Image Software Volumes on page 32 and Using the Sun SNDR Software With Sun StorEdge Instant Image Software on page 63 If autosynchronization is on if the volume specified as the Sun StorEdge Instant Image shadow of the Sun SNDR software secondary volume is mounted the Sun SNDR software secondary volume data will be in an unknown state when the Sun SNDR software starts a synchronization If this state is not appropriate for a Sun StorEdge Instant Image snapshot do not put the Sun SNDR software into autosynchronization mode 80 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 6 After the disk failure is corrected and any related Volume Manager volumes are recreated use this command to perform the following reverse synchronization while the primary affected volumes are unmounted hostl sndradm m r g io groupname C tag n config file SNDR set set name This command starts reverse full synchronization as the secondary volume on host2 is resynchronizing the new primary volume on host 1 FIGURE 4 6 shows the full reverse synchronization process 1 The data might already b
91. ume on page 80 but a larger number of devices is included in the reverse resynchronization request Chapter 4 Using The Sun SNDR Software to Restore Volumes and Sites 85 Site A Primary Remote Site B Secondary Disk Disk Cache HBA HBA Cache Sun _ hosti host2 SNDR lee f a 1 Vv LI Replaced Up to date V 2 I disk ATM secondary disk 2R Indicates one transmit and one receive fiber used in intersite fiber link FIGURE 4 8 Restoring the Primary Site from the Secondary Site Disabling Remote Replication Caution Disable remote replication only when it is not necessary that the primary and secondary volumes be associated with each other any longer Disabling the Sun SNDR software breaks the connection between primary and secondary volumes discards any scoreboards and removes the host and volume information from the data services configuration Following the Sun SNDR software disable enable and full synchronization full volume copy operations will be necessary to re establish the Sun SNDR software relationship and ensure that the volumes contents match See Enabling the Sun SNDR Software on page 28 and Full Forward Synchronization Establishing Replicated Images for the First Time on page 64 86 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001
92. up GL 2 rolling disaster GL 2 synchronization GL 3 synchronous mirroring GL 3 toggle the autosynchronization state 49 U update bitmap in a volume set 40 disk cluster tag name 46 I O group 44 Sun SNDR configuration 45 update synchronization 68 GL 3 updating primary site 83 V volume set GL 3 reset the replication mode 47 volumes see disk GL 3 selecting 61 volume to volume copy 65 W wait for synchronization to complete command 38 Index 3 Index 4 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001
93. vent of a failure a read is attempted on each set member until a successful read is accomplished The process of maintaining two or more identical images of a designated disk volume A process where each server can concurrently transmit and receive copies to and from its remote counterpart Each system contains primary disks in a Sun SNDR software volume set that are accessible by local hosts as well as remote mirrors secondary to remote hosts Mutual backup might be used where critical applications and storage are split across sites and both sites require remote redundant copies UNIX device names of the form dev rdsk cntndnsn associated with the host disks on a Solaris system The system or volume being accessed directly by the host application System or volume on which the host application is principally dependent To stop operations of a database application momentarily so that Sun SNDR software update and copy operations will not encounter data errors After the update or copy command is issued the database application can be restarted Redundant Arrays of Independent Disks A resynchronization operation that discards any blocks modified during recovery rehearsals Scoreboard logging keeps track of test updates applied to the secondary system during the rehearsal When the primary is restored the test updates are overwritten with the blocks from the primary image restoring matching remote sets A collection of damaging event
94. ynchronization Update Resynchronizing Volumes After an Interruption both sites before invoking it While resynchronization is occurring the secondary volumes are temporarily inconsistent and cannot be relied on for recovery Consistency is restored when the resynchronization finishes executing To ensure data integrity use the Instant Image software regularly to create a point in time copy of data at both sites 1 Caution Ensure that you understand the resynchronization process of updating Typically interruptions in the Sun SNDR software services are infrequent The type of interruption an isolated incident or part of a larger disaster determines the action you should take If the Sun SNDR software interruption is a symptom of a larger rolling disaster avoid resynchronization of the sites Maintain the secondary site in a dated but consistent state rather than risk a disastrous interruption that leaves the secondary site inconsistent and difficult to recover from 66 Sun StorEdge Network Data Replicator 3 0 System Administrator s Guide June 2001 v To Enable Update Synchronization When you determine that the Sun SNDR software interruption is an isolated incident and the condition has been repaired enable update synchronization using the following Sun SNDR software command host1 sndradm u g io groupname C tag n config file SNDR set set name Note If the secondary volume state i
95. zed from its source primary volume However restoration of a failed primary volume might require reverse synchronization using the surviving remote mirror as the source Signal sent by each system to its remote set confirming that it is operational The absence of a health monitor signal is the first indication that the intersite link or remote system is impaired Head disk assembly A collection of Sun SNDR software volume sets that have the same group name primary and secondary hosts and mirroring mode A mirrored partition or RAID 1 volume which are established in a single system and do not rely on the Sun SNDR software or any hardware to maintain local synchronization See mirrored partitions Glossary 1 logging mirrored partitions mirroring mutual backup partitions primary quiesce RAID rollback synchronization rolling disaster scoreboard log A method for tracking volume updates that have not been remotely copied while the remote service is interrupted or impaired The blocks that no longer match their remote sets are identified for each volume The Sun SNDR software uses these logs scoreboards to re establish matching sets through an optimized update synchronization rather than through a complete volume to volume copy Multiple copies of disk partitions that provide RAID 1 protection against possible data loss from disk failure Data can be read back from any of the members in the set in the e

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