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Wiley Cloud Computing: Principles and Paradigms

1. SM TTD seg sn s3urpurg asensury 21 809 IN WAMO Qd1A19G Se PNO TI ATAV L 29 30 INTRODUCTION TO CLOUD COMPUTING Flexiscale Flexiscale is a UK based provider offering services similar in nature to Amazon Web Services However its virtual servers offer some distinct features most notably persistent storage by default fixed IP addresses dedicated VLAN a wider range of server sizes and runtime adjustment of CPU capacity aka CPU bursting vertical scaling Similar to the clouds this service is also priced by the hour In summary the Flexiscale cloud provides the following features available in UK Web services SOAP Web based user interfaces access to virtual server mainly via SSH Linux and Remote Desktop Windows 100 availability SLA with automatic recovery of VMs in case of hardware failure per hour pricing Linux and Windows operating systems automatic scaling horizontal vertical Joyent Joyent s Public Cloud offers servers based on Solaris containers virtualization technology These servers dubbed accelerators allow deploying various specialized software stack based on a customized version of Open Solaris operating system which include by default a Web based configuration tool and several pre installed software such as Apache MySQL PHP Ruby on Rails and Java Sof
2. Heroku Heroku is a platform for instant deployment of Ruby on Rails Web applications In the Heroku system servers are invisibly managed by the platform and are never exposed to users Applications are automatically dispersed across different CPU cores and servers maximizing performance and minimizing contention Heroku has an advanced logic layer than can automatically route around failures ensuring seamless and uninterrupted service at all times 1 8 CHALLENGES AND RISKS Despite the initial success and popularity of the cloud computing paradigm and the extensive availability of providers and tools a significant number of challenges and risks are inherent to this new model of computing Providers developers and end users must consider these challenges and risks to take good advantage of cloud computing Issues to be faced include user privacy data 1 8 CHALLENGES AND RISKS 35 security data lock in availability of service disaster recovery performance scalability energy efficiency and programmability 1 8 1 Security Privacy and Trust Ambrust et al 5 cite information security as a main issue current cloud offerings are essentially public exposing the system to more attacks For this reason there are potentially additional challenges to make cloud computing environments as secure as in house IT systems At the same time existing well understood technologies can be leveraged such as data encryption VLANs an
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4. Elasticity can be achieved by combining the CloudWatch Auto Scaling and Elastic Load Balancing features which allow the number of instances to scale up and down automatically based on a set of customizable rules and traffic to be distributed across available instances Fixed IP address Elastic IPs are not available by default but can be obtained at an additional cost In summary Amazon EC2 provides the following features multiple data centers available in the United States East and West and Europe CLI Web services SOAP and Query Web based console user interfaces access to instance mainly via SSH Linux and Remote Desktop Windows advanced reservation of capacity aka reserved instances that guarantees availability for periods of 1 and 3 years 99 5 availability SLA per hour pricing Linux and Windows operating systems automatic scaling load balancing 4 http aws amazon com 1504 5 Jamod 9215 o 001 dn Ajyeuonsodoid 81 1 g9 0 soumnbo 90 079 01 91 7 0 SAd 01 dn 99 sunsing 90 001 5 55 550 5 0 8 91 1 ao D 087 08 8 50 SNdO 9 1 100421 80 80 0LT 0T 91 50 5 t I 105592014 581 199 suun 911 901 aD ayndwioo 90
5. The development of standardized protocols for several grid computing activities has contributed theoretically to allow delivery of on demand computing services over the Internet However ensuring QoS in grids has been perceived as a difficult endeavor 19 Lack of performance isolation has prevented grids adoption in a variety of scenarios especially on environ ments where resources are oversubscribed or users are uncooperative Activities associated with one user or virtual organization VO can influence in an uncontrollable way the performance perceived by other users using the same platform Therefore the impossibility of enforcing QoS and guaranteeing execution time became a problem especially for time critical applications 20 Another issue that has lead to frustration when using grids is the availability of resources with diverse software configurations including disparate operating systems libraries compilers runtime environments and so forth At the same time user applications would often run only on specially customized environ ments Consequently a portability barrier has often been present on most grid infrastructures inhibiting users of adopting grids as utility computing environments 20 Virtualization technology has been identified as the perfect fit to issues that have caused frustration when using grids such as hosting many dissimilar software applications on a single physical platform In this direction some
6. ADCOM 2009 Ben galuru India 2009 VMWare Inc VMware High Availability HA Attp www vmware com products high availability index html 22 4 2010 Citrix Systems Inc The three levels of high availability Balancing priorities and cost White Paper 2008 VMWare Inc VMWare vStorage APIs for Data Protection http www vmware com products vstorage apis for data protection 22 4 2010 H E Schaffer et al NCSUs Virtual Computing Lab A cloud computing solution Computer 42 94 97 2009 North Carolina State University Virtual Computing Lab VCL Attp vcl ncsu edu 22 4 2010 3tera Inc AppLogic Grid Operating System for Web Applications http www 3tera com AppLogic 22 4 2010 3Tera Inc The AppLogic Grid Operating System White Paper 2006 64 65 66 67 68 69 70 71 T2 73 74 REFERENCES 41 Citrix Systems Inc Citrix essentials for Hyper V http www citrix com ehy 22 4 2010 Distributed Systems Architecture Group OpenNebula The open source toolkit for cloud computing Attp www opennebula org 22 4 2010 University of Chicago Haizea An open source VM based lease manager ittp haizea cs uchicago edu 22 4 2010 Red Hat s Emerging Technology group oVirt http ovirt org 22 4 2010 Platform Computing Corporation Platform ISF ttp www platform com Products platform isf 22 4 2010 Platform Computing Platform Orchestrator ttp www platfo
7. research projects e g Globus Virtual Workspaces 20 aimed at evolving grids to support an additional layer to virtualize computation storage and network resources 1 2 4 Utility Computing With increasing popularity and usage large grid installations have faced new problems such as excessive spikes in demand for resources coupled with strategic and adversarial behavior by users Initially grid resource management techniques did not ensure fair and equitable access to resources in many systems Traditional metrics throughput waiting time and slowdown failed to capture the more subtle requirements of users There were no real incentives for users to be flexible about resource requirements or job deadlines nor provisions to accommodate users with urgent work In utility computing environments users assign a utility value to their jobs where utility is a fixed or time varying valuation that captures various QoS constraints deadline importance satisfaction The valuation is the amount they are willing to pay a service provider to satisfy their demands The service providers then attempt to maximize their own utility where said utility may directly correlate with their profit Providers can choose to prioritize 43 10 INTRODUCTION TO CLOUD COMPUTING high yield i e profit per unit of resource user jobs leading to a scenario where shared systems are viewed as a marketplace where users compete for resources based on th
8. such as AR a VI manager must allow users to lease resources expressing more complex terms e g the period of time of a reservation This is especially useful in clouds on which resources are scarce since not all requests may be satisfied immediately they can benefit of VM placement strategies that support queues priorities and advance reservations 55 Additionally leases may be negotiated and renegotiated allowing provider and consumer to modify a lease or present counter proposals until an agreement is reached This feature is illustrated by the case in which an AR request for a given slot cannot be satisfied but the provider can offer a distinct slot that is still satisfactory to the user This problem has been addressed in OpenPEX which incorporates a bilateral negotiation protocol that allows users and providers to come to an alternative agreement by exchanging offers and counter offers 56 High Availability and Data Recovery The high availability HA feature of VI managers aims at minimizing application downtime and preventing business disruption A few VI managers accomplish this by providing a failover mechanism which detects failure of both physical and virtual servers and restarts VMs on healthy physical servers This style of HA protects from host but not VM failures 57 58 For mission critical applications when a failover solution involving restart ing VMs does not suffice additional levels of fault tolera
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10. Apache Foundation Since its inception the main objective of VCL has been providing desktop virtual lab and HPC computing environments anytime in a flexible cost effective way and with minimal intervention of IT staff In this sense VCL was one of the first projects to create a tool with features such as self service Web portal to reduce administrative burden advance reservation of capacity to provide resources during classes and deployment of customized machine images on multiple computers to provide clusters on demand In summary Apache VCL provides the following features i multi platform controller based Apache PHP ii Web portal and XML RPC interfaces 11 support for VMware hypervisors ESX ESXi and Server iv virtual networks v virtual clusters and vi advance reservation of capacity AppLogic AppLogic 62 is a commercial VI manager the flagship product of 3tera Inc from California USA The company has labeled this product as a Grid Operating System AppLogic provides a fabric to manage clusters of virtualized servers focusing on managing multi tier Web applications It views an entire applica tion as a collection of components that must be managed as a single entity Several components such as firewalls load balancers Web servers application servers and database servers can be set up and linked together Whenever the application is started the system manufactures and assembles the virtual infrast
11. Data Center when private cloud interna capacity is Private Enterprise Clouds Public Internet Clouds La DI 3rd party multi tenant Cloud infrastructure amp services available on subscription basis pay as you go insufficient FIGURE 1 4 Types of clouds based on deployment models 16 INTRODUCTION TO CLOUD COMPUTING Armbrust et al 5 propose definitions for public cloud as a cloud made available in a pay as you go manner to the general public and private cloud as internal data center of a business or other organization not made available to the general public In most cases establishing a private cloud means restructuring an existing infrastructure by adding virtualization and cloud like interfaces This allows users to interact with the local data center while experiencing the same advantages of public clouds most notably self service interface privileged access to virtual servers and per usage metering and billing A community cloud is shared by several organizations and supports a specific community that has shared concerns e g mission security require ments policy and compliance considerations 6 A hybrid cloud takes shape when a private cloud is supplemented with computing capacity from public clouds 7 The approach of temporarily renting capacity to handle spikes in load is known as cloud bursting 42 1 4 DESIRED FEATU
12. Mainframes to Clouds We are currently experiencing a switch in the IT world from in house generated computing power into utility supplied computing resources delivered over the Internet as Web services This trend is similar to what occurred about a century ago when factories which used to generate their own electric power realized that it is was cheaper just plugging their machines into the newly formed electric power grid 8 Computing delivered as a utility can be defined as demand delivery of infrastructure applications and business processes in a security rich shared scalable and based computer environment over the Internet for a fee 9 6 INTRODUCTION TO CLOUD COMPUTING Hardware Hardware Virtualization Multi core chips SOA Web 2 0 Web Services Mashups Utility amp Grid Computing Distributed Computing Autonomic Computing Data Center Automation Systems Management FIGURE 1 1 Convergence of various advances leading to the advent of cloud computing This model brings benefits to both consumers and providers of IT services Consumers can attain reduction on IT related costs by choosing to obtain cheaper services from external providers as opposed to heavily investing on IT infrastructure and personnel hiring The on demand component of this model allows consumers to adapt their IT usage to rapidly increasing or unpredic
13. and emerging IT platforms Vision hype and reality for delivering computing as the 5th utility Future Generation Computer Systems 25 599 616 2009 3 Vaquero L Rodero Merino J Caceres and Lindner A break in the clouds Towards a cloud definition STGCOMM Computer Communications Review 39 50 55 2009 4 McKinsey amp Co Clearing the Air on Cloud Computing Technical Report 2009 38 10 11 12 13 14 15 16 17 18 19 20 21 INTRODUCTION TO CLOUD COMPUTING M Armbrust A Fox R Griffith A D Joseph and R Katz Above the Clouds A Berkeley View of Cloud Computing UC Berkeley Reliable Adaptive Distributed Systems Laboratory White Paper 2009 P Mell and T Grance The NIST Definition of Cloud Computing National Institute of Standards and Technology Information Technology Laboratory Technical Report Version 15 2009 B Sotomayor R S Montero I M Llorente and I Foster Virtual infrastructure management in private and hybrid clouds IEEE Internet Computing 13 5 14 22 September October 2009 N Carr The Big Switch Rewiring the World from Edison to Google W W Norton amp Co New York 2008 M A Rappa The utility business model and the future of computing systems IBM Systems Journal 43 1 32 42 2004 S Yeo et al Utility computing on global grids Chapter 143 Hossein Bidgoli ed The Handbook of Computer Networks ISBN 978 0 471
14. enables the sharing of solutions developed by third party developers on top of Salesforce com components 1 2 3 Grid Computing Grid computing enables aggregation of distributed resources and transparently access to them Most production grids such as TeraGrid 15 and EGEE 16 seek to share compute and storage resources distributed across different administrative domains with their main focus being speeding up a broad range of scientific applications such as climate modeling drug design and protein analysis A key aspect of the grid vision realization has been building standard Web services based protocols that allow distributed resources to be discovered accessed allocated monitored accounted for and billed for etc and in general managed as a single virtual system The Open Grid Services Archi tecture OGSA addresses this need for standardization by defining a set of core capabilities and behaviors that address key concerns in grid systems l http www programmableweb com 2 http sites force com appexchange 1 2 ROOTS OF CLOUD COMPUTING 9 Globus Toolkit 18 is a middleware that implements several standard Grid services and over the years has aided the deployment of several service oriented Grid infrastructures and applications An ecosystem of tools is available to interact with service grids including grid brokers which facilitate user inter action with multiple middleware and implement policies to meet QoS needs
15. just for what is really needed This introductory chapter has surveyed many technologies that have led to the advent of cloud computing concluding that this new paradigm has been a result of an evolution rather than a revolution In their various shapes and flavors clouds aim at offering compute storage network software or a combination of those as a service Infrastructure Platform and Software as a service are the three most common nomencla tures for the levels of abstraction of cloud computing services ranging from raw virtual servers to elaborate hosted applications A great popularity and apparent success have been visible in this area However as discussed in this chapter significant challenges and risks need to be tackled by industry and academia in order to guarantee the long term success of cloud computing Visible trends in this sphere include the emergence of standards the creation of value added services by augmenting combining and brokering existing compute storage and software services and the availability of more providers in all levels thus increasing competiveness and innovation In this sense numerous opportunities exist for practitioners seeking to create solutions for cloud computing REFERENCES 1 I Foster The grid Computing without bounds Scientific American vol 288 No 4 April 2003 78 85 2 Buyya 5 Yeo S Venugopal J Broberg and I Brandic Cloud computing
16. logic 12 This concept of gluing services initially focused on the enterprise Web but gained space in the consumer realm as well especially with the advent of Web 2 0 In the consumer Web information and services may be programmatically aggregated acting as building blocks of complex compositions called service mashups Many service providers such as Amazon del icio us Facebook and Google make their service APIs publicly accessible using standard protocols such as SOAP and REST 14 Consequently one can put an idea of a fully functional Web application into practice just by gluing pieces with few lines of code In the Software as a Service SaaS domain cloud applications can be built as compositions of other services from the same or different providers Services such user authentication e mail payroll management and calendars are examples of building blocks that can be reused and combined in a business solution in case a single ready made system does not provide all those features Many building blocks and solutions are now available in public marketplaces For example Programmable Web is a public repository of service APIs and mashups currently listing thousands of APIs and mashups Popular APIs such as Google Maps Flickr YouTube Amazon eCommerce and Twitter when combined produce a variety of interesting solutions from finding video game retailers to weather maps Similarly Salesforce com s offers AppExchange which
17. that the additional resources can be a provisioned possibly automatically when an application load increases and b released when load decreases scale up and down 6 1 4 4 Customization In a multi tenant cloud a great disparity between user needs is often the case Thus resources rented from the cloud must be highly customizable In the case of infrastructure services customization means allowing users to deploy specialized virtual appliances and to be given privileged root access to the virtual servers Other service classes PaaS and SaaS offer less flexibility and are not suitable for general purpose computing 5 but still are expected to provide a certain level of customization 1 5 CLOUD INFRASTRUCTURE MANAGEMENT A key challenge IaaS providers face when building a cloud infrastructure is managing physical and virtual resources namely servers storage and net works in a holistic fashion 43 The orchestration of resources must be performed in a way to rapidly and dynamically provision resources to applications 7 The software toolkit responsible for this orchestration is called a virtual infrastructure manager VIM 7 This type of software resembles a traditional operating system but instead of dealing with a single computer it aggregates resources from multiple computers presenting a uniform view to user and applications The term cloud operating system is also used to refer to it 43 Other terms inclu
18. the capabilities of an Aneka Cloud node thus providing a single extensible framework for orchestrating various application models Several programming models are supported by such task models to enable execution of legacy HPC applications and MapReduce which enables a variety of data mining and search applications Users request resources via a client to a reservation services manager of the Aneka master node which manages all cloud nodes and contains scheduling service to distribute request to cloud nodes App Engine Google App Engine lets you run your Python and Java Web applications on elastic infrastructure supplied by Google App Engine allows your applications to scale dynamically as your traffic and data storage requirements increase or decrease It gives developers a choice between a Python stack and Java The App Engine serving architecture is notable in that it allows real time auto scaling without virtualization for many common types of Web applications However such auto scaling is dependent on the FFO A poseq suvog Pd 19N ears Inpo yde WN 95 TOJ uozewy 814 oH 3115590044 eq uozewy vozeury paseq 51001 TOJ Sox 108218504 jsonboy Aqny nyo1oH 991
19. 19 TOS 5 980108 SOX 4019 198 L 10 5100 oinzy pu IJOSIN 8 poseq ds 5 OMI 9OXY 9 AAI yoolqo poseq asdioq xody W109 9910 4 Surmueis01d 5 sox 1 814 poseq jsonboy poseq osdijoq eae ouisuqddy OdH SAGH SWAAN sonpoy del AAS suoneodde TOJ ON sory WJA LAN JON Byouy 3019 suondo S SPO SYIOMOWPL IN 1 8 5 9219351519 8218027 puoyoeg 180 1 SUNJO PNO JO 1 AIAVL 33 34 INTRODUCTION TO CLOUD COMPUTING application developer using a limited subset of the native APIs on each platform and in some instances you need to use specific Google APIs such as URLFetch Datastore and memcache in place of certain native API calls For example a deployed App Engine application cannot write to the fi
20. 78461 6 John Wiley amp Sons New York USA 2007 I Foster and S Tuecke Describing the elephant The different faces of IT as service ACM Queue 3 6 26 29 2005 M P Papazoglou and W J van den Heuvel Service oriented architectures Approaches technologies and research issues The VLDB Journal 16 389 415 2007 H Kreger Fulfilling the Web services promise Communications of the ACM 46 6 29 2003 Blau D Neumann Weinhardt and S Lamparter Planning and pricing of service mashups in Proceedings of the 2008 10th IEEE Conference on E Commerce Technology and the Fifth IEEE Conference on Enterprise Computing E Commerce and E Services Crystal City Washington DC 2008 pp 19 26 C Catlett The philosophy of TeraGrid Building an open extensible distributed TeraScale facility in Proceedings of 2nd IEEE ACM International Symposium on Cluster Computing and the Grid Berlin Germany 2002 p 8 F Gagliardi B Jones F Grey M E Begin and M Heikkurinen Building an infrastructure for scientific grid computing Status and goals of the EGEE project Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences 363 1833 1729 2005 J Broberg Venugopal and Buyya Market oriented Grid and utility computing The state of the art and future directions Journal of Grid Computing 6 255 276 2008 I Foster Globus toolkit version 4 Software for service oriented sys
21. MWare Inc VMWare Virtual Appliance Marketplace http www vmware com appliances 22 4 2010 Amazon Web Services Developer Community Amazon Machine Images ttp developer amazonwebservices com connect kbcategory jspa categoryID 171 22 4 2010 Distributed Management Task Force Inc Open Virtualization Format Specifica tion DSP0243 Version 1 0 0 2009 J Matthews T Garfinkel C Hoff and J Wheeler Virtual machine contracts for datacenter and cloud computing environments in Proceedings of the Ist Workshop on Automated Control for Datacenters and Clouds 2009 pp 25 30 International Business Machines Corp An architectural blueprint for autonomic computing White Paper Fourth Edition 2006 M C Huebscher and J A McCann A survey of autonomic computing degrees models and applications ACM Computing Surveys 40 1 28 2008 VMWare Inc VMware vSphere ttp www vmware com products vsphere 22 4 2010 L Youseff M Butrico and D Da Silva Toward a unified ontology of cloud computing in Proceedings of the 2008 Grid Computing Environments Workshop 2008 1 10 Buyya 5 Pandey and Vecchiola Cloudbus toolkit for market oriented cloud computing in Proceedings Ist International Conference on Cloud Computing CloudCom 09 Beijing 2009 pp 3 27 D Nurmi Wolski Grzegorczyk G Obertelli S Soman L Youseff and Zagorodnov The Eucalyptus open source cloud computing system in Proce
22. Nebula also supports advance reservation of capacity and queuing of best effort leases 7 In summary OpenNebula provides the following features Linux based controller CLI XML RPC EC2 compatible Query and OCA interfaces Xen KVM and VMware backend interface to public clouds Amazon EC2 ElasticHosts virtual networks dynamic resource allocation advance reserva tion of capacity OpenPEX OpenPEX Open Provisioning and EXecution Environment was constructed around the notion of using advance reservations as the primary method for allocating VM instances It distinguishes from other VI managers by its leases negotiation mechanism which incorporates a bilateral negotiation protocol that allows users and providers to come to an agreement by exchanging offers and counter offers when their original requests cannot be satisfied In summary OpenPEX provides the following features multi platform Java controller Web portal and Web services REST interfaces Citrix XenServer backend advance reservation of capacity with negotiation 56 oVirt oVirt is an open source VI manager sponsored by Red Hat s Emergent Technology group It provides most of the basic features of other VI managers 1 5 CLOUD INFRASTRUCTURE MANAGEMENT 25 including support for managing physical server pools storage pools user accounts and VMs All features are accessible through a Web interface 67 The oVirt admin node which is also a VM provides a Web ser
23. PART FOUNDATIONS CHAPTER 1 INTRODUCTION TO CLOUD COMPUTING WILLIAM VOORSLUYS JAMES BROBERG and RAJKUMAR BUYYA 11 CLOUD COMPUTING IN A NUTSHELL When plugging an electric appliance into an outlet we care neither how electric power is generated nor how it gets to that outlet This is possible because electricity is virtualized that is it is readily available from a wall socket that hides power generation stations and a huge distribution grid When extended to information technologies this concept means delivering useful functions while hiding how their internals work Computing itself to be considered fully virtualized must allow computers to be built from distributed components such as processing storage data and software resources 1 Technologies such as cluster grid and now cloud computing have all aimed at allowing access to large amounts of computing power in a fully virtualized manner by aggregating resources and offering a single system view In addition an important aim of these technologies has been delivering computing as a utility Utility computing describes a business model for on demand delivery of computing power consumers pay providers based on usage as you go similar to the way in which we currently obtain services from traditional public utility services such as water electricity gas and telephony Cloud computing has been coined as an umbrella term to describe a category of s
24. RES OF A CLOUD Certain features of a cloud are essential to enable services that truly represent the cloud computing model and satisfy expectations of consumers and cloud offerings must be 1 self service ii per usage metered and billed iii elastic and iv customizable 1 4 1 Self Service Consumers of cloud computing services expect on demand nearly instant access to resources To support this expectation clouds must allow self service access so that customers can request customize pay and use services without intervention of human operators 6 1 4 2 Per Usage Metering and Billing Cloud computing eliminates up front commitment by users allowing them to request and use only the necessary amount Services must be priced on a short term basis e g by the hour allowing users to release and not pay for resources as soon as they are not needed 5 For these reasons clouds must implement features to allow efficient trading of service such as pricing accounting and billing 2 Metering should be done accordingly for different types of service e g storage processing and bandwidth and usage promptly reported thus providing greater transparency 6 1 4 3 Elasticity Cloud computing gives the illusion of infinite computing resources available on demand 5 Therefore users expect clouds to rapidly provide resources in any 1 5 CLOUD INFRASTRUCTURE MANAGEMENT 17 quantity at any time In particular it is expected
25. VMWare vCloud and Citrix Cloud Center C3 which have lowered the barrier of entry for laaS competitors leading to a rapid expansion in the IaaS marketplace 1 6 2 Case Studies In this section we describe the main features of the most popular public IaaS clouds Only the most prominent and distinguishing features of each one are discussed in detail A detailed side by side feature comparison of IaaS offerings is presented in Table 1 2 Amazon Web Services Amazon WS AWS is one of the major players in the cloud computing market It pioneered the introduction of IaaS clouds in 2006 It offers a variety cloud services most notably S3 storage EC2 virtual servers Cloudfront content delivery Cloudfront Streaming video stream ing SimpleDB structured datastore RDS Relational Database SQS reliable messaging and Elastic MapReduce data processing The Elastic Compute Cloud EC2 offers Xen based virtual servers instances that can be instantiated from Amazon Machine Images AMIs Instances are available in a variety of sizes operating systems architectures and price CPU capacity of instances is measured in Amazon Compute Units and although fixed for each instance vary among instance types from 1 small instance to 20 high CPU instance Each instance provides a certain amount of nonpersistent disk space a persistence disk service Elastic Block Storage allows attaching virtual disks to instances with space up to ITB
26. are characteristics e g memory network cards and disks operating system details startup and shutdown actions the virtual disks themselves and other metadata containing product and licensing information OVF also supports complex packages composed of multiple VMs e g multi tier applications 32 OVF s extensibility has encouraged additions relevant to management of data centers and clouds Mathews et al 33 have devised virtual machine contracts VMC as an extension to OVF A VMC aids in communicating and managing the complex expectations that VMs have of their runtime environ ment and vice versa A simple example of a VMC is when a cloud consumer wants to specify minimum and maximum amounts of a resource that a VM needs to function similarly the cloud provider could express resource limits as a way to bound resource consumption and costs 1 3 LAYERS AND TYPES OF CLOUDS 13 1 2 7 Autonomic Computing The increasing complexity of computing systems has motivated research on autonomic computing which seeks to improve systems by decreasing human involvement in their operation In other words systems should manage themselves with high level guidance from humans 34 Autonomic or self managing systems rely on monitoring probes and gauges sensors on an adaptation engine autonomic manager for computing optimizations based on monitoring data and on effectors to carry out changes on the system IBM s Autonomic Computing In
27. ble feature of a VI manager Multiple Backend Hypervisors Different virtualization models and tools offer different benefits drawbacks and limitations Thus some VI managers provide a uniform management layer regardless of the virtualization technol ogy used This characteristic is more visible in open source VI managers which usually provide pluggable drivers to interact with multiple hypervisors 7 In this direction the aim of libvirt 47 is to provide a uniform API that VI managers can use to manage domains a VM or container running an instance of an operating system in virtualized nodes using standard operations that abstract hypervisor specific calls Storage Virtualization Virtualizing storage means abstracting logical sto rage from physical storage By consolidating all available storage devices in a data center it allows creating virtual disks independent from device and location Storage devices are commonly organized in a storage area network SAN and attached to servers via protocols such as Fibre Channel iSCSI and 1 5 CLOUD INFRASTRUCTURE MANAGEMENT 19 NFS a storage controller provides the layer of abstraction between virtual and physical storage 48 In the VI management sphere storage virtualization support is often restricted to commercial products of companies such as VMWare and Citrix Other products feature ways of pooling and managing storage devices but administrators are still aware of each individual de
28. by service providers to build public clouds In terms of interfacing with public clouds vSphere interfaces with the vCloud API thus enabling cloud bursting into external clouds In summary vSphere provides the following features Windows based controller vCenter Server CLI GUI Web portal and Web services interfaces VMware ESX ESXi backend VMware vStorage VMFS storage virtualization interface to external clouds VMware vCloud partners virtual networks VMWare Distributed Switch dynamic resource allocation VMware DRM high availability data protection VMWare Consolidated Backup 1 6 INFRASTRUCTURE AS A SERVICE PROVIDERS Public Infrastructure as a Service providers commonly offer virtual servers containing one or more CPUs running several choices of operating systems and a customized software stack In addition storage space and communica tion facilities are often provided 1 6 1 Features In spite of being based on a common set of features IaaS offerings can be distinguished by the availability of specialized features that influence the cost benefit ratio to be experienced by user applications when moved to the cloud The most relevant features are 1 geographic distribution of data centers ii variety of user interfaces and APIs to access the system specialized components and services that aid particular applications e g load balancers firewalls iv choice of virtualization platform and operating syste
29. ctice is also employed for overcoming potential software and hardware incompatibilities in case of upgrades given that it is possible to run legacy and new operation systems concurrently 22 Workload migration also referred to as application mobility 23 targets at facilitating hardware maintenance load balancing and disaster recovery It is done by encapsulating a guest OS state within a VM and allowing it to be suspended fully serialized migrated to a different platform and resumed immediately or preserved to be restored at a later date 22 A VM s state includes a full disk or partition image configuration files and an image of its RAM 20 A number of VMM platforms exist that are the basis of many utility or cloud computing environments The most notable ones VMWare Xen and KVM are outlined in the following sections VMWare ESXi VMware is a pioneer in the virtualization market Its ecosys tem of tools ranges from server and desktop virtualization to high level management tools 24 ESXi is VMM from VMWare It is a bare metal hypervisor meaning that it installs directly on the physical server whereas others may require a host operating system It provides advanced virtualization techniques of processor memory and I O Especially through memory ballooning and page sharing it can overcommit memory thus increasing the density of VMs inside a single physical server Xen The Xen hypervisor started as an open source
30. d firewalls Security and privacy affect the entire cloud computing stack since there is a massive use of third party services and infrastructures that are used to host important data or to perform critical operations In this scenario the trust toward providers is fundamental to ensure the desired level of privacy for applications hosted in the cloud 38 Legal and regulatory issues also need attention When data are moved into the Cloud providers may choose to locate them anywhere on the planet The physical location of data centers determines the set of laws that can be applied to the management of data For example specific cryptography techniques could not be used because they are not allowed in some countries Similarly country laws can impose that sensitive data such as patient health records are to be stored within national borders 1 8 2 Data Lock In and Standardization A major concern of cloud computing users is about having their data locked in by a certain provider Users may want to move data and applications out from a provider that does not meet their requirements However in their current form cloud computing infrastructures and platforms do not employ standard methods of storing user data and applications Consequently they do not interoperate and user data are not portable The answer to this concern is standardization In this direction there are efforts to create open standards for cloud computing The Cloud Comput
31. de infrastructure sharing software 44 and virtual infra structure engine 45 Sotomayor et al 7 in their description of the cloud ecosystem of software tools propose a differentiation between two categories of tools used to manage clouds The first category cloud toolkits includes those that expose a remote and secure interface for creating controlling and monitoring virtualize resources but do not specialize in VI management Tools in the second category the virtual infrastructure managers provide advanced features such as automatic load balancing and server consolidation but do not expose remote cloud like interfaces However the authors point out that there is a superposition between the categories cloud toolkits can also manage virtual infrastructures although they usually provide less sophisticated features than specialized VI managers do The availability of a remote cloud like interface and the ability of managing many users and their permissions are the primary features that would distinguish cloud toolkits from VIMs However in this chapter we place both categories of tools under the same group of the VIMs and when applicable we highlight the availability of a remote interface as a feature 18 INTRODUCTION TO CLOUD COMPUTING Virtually all VIMs we investigated present a set of basic features related to managing the life cycle of VMs including networking groups of VMs together and se
32. de available over the Internet Over the years a rich WS software stack has been specified and standardized resulting in a multitude of technologies to describe compose and orchestrate services package and transport messages between services publish and dis cover services represent quality of service QoS parameters and ensure security in service access 13 WS standards have been created on top of existing ubiquitous technologies such as HTTP and XML thus providing a common mechanism for delivering services making them ideal for implementing a service oriented architecture SOA The purpose of a SOA is to address requirements of loosely coupled standards based and protocol independent distributed computing In a SOA software resources are packaged as services which are well defined self contained modules that provide standard business functionality and are independent of the state or context of other services Services are described in a standard definition language and have a published interface 12 The maturity of WS has enabled the creation of powerful services that can be accessed on demand in a uniform way While some WS are published with the 8 INTRODUCTION TO CLOUD COMPUTING intent of serving end user applications their true power resides in its interface being accessible by other services An enterprise application that follows the SOA paradigm is a collection of services that together perform complex business
33. dings of the 2008 ACM IEEE Conference on Supercomputing 2008 pp 1 12 R Perlman Interconnections Bridges Routers Switches and Internetworking Protocols Addison Wesley Longman Boston MA 1999 8 Tanenbaum Computer Networks Prentice Hall Upper Saddle River NJ 2002 D Gmach J Rolia L Cherkasova and A Kemper Capacity management and demand prediction for next generation data centers in Proceedings of IEEE International Conference on Web Services 2007 pp 43 50 A Verma P Ahuja and A Neogi pMapper Power and migration cost aware application placement in virtualized systems in Proceedings of the 9th ACM IFIP USENIX International Conference on Middleware 2008 pp 243 264 K Keahey and T Freeman Contextualization Providing one click virtual clusters in Proceedings of IEEE Fourth International Conference on eScience 2008 pp 301 308 B Sotomayor K Keahey and I Foster Combining batch execution and leasing using virtual machines in Proceedings of the 17th International Symposium on High Performance Distributed Computing 2008 pp 87 96 B Sotomayor R Montero I M Llorente and I Foster Capacity leasing in cloud systems using the opennebula engine Cloud Computing and Applications 2008 S Venugopal J Broberg and R Buyya OpenPEX An open provisioning and EXecution system for virtual machines in Proceedings of the 17th International Conference on Advanced Computing and Communications
34. e perceived utility or value of their jobs Further information and comparison of these utility computing environments are available in an extensive survey of these platforms 17 1 2 5 Hardware Virtualization Cloud computing services are usually backed by large scale data centers composed of thousands of computers Such data centers are built to serve many users and host many disparate applications For this purpose hardware virtualization can be considered as a perfect fit to overcome most operational issues of data center building and maintenance The idea of virtualizing a computer system s resources including processors memory and I O devices has been well established for decades aiming at improving sharing and utilization of computer systems 21 Hardware virtua lization allows running multiple operating systems and software stacks on a single physical platform As depicted in Figure 1 2 a software layer the virtual machine monitor VMM also called a hypervisor mediates access to the physical hardware presenting to each guest operating system a virtual machine VM which is a set of virtual platform interfaces 22 The advent of several innovative technologies multi core chips paravir tualization hardware assisted virtualization and live migration of VMs has contributed to an increasing adoption of virtualization on server systems Traditionally perceived benefits were improvements on sharing and utilization better
35. edings of IEEE ACM International Symposium on Cluster Computing and the Grid CCGrid 2009 Shanghai China pp 124 131 University of California Santa Barbara 2009 Sep Eucalyptus online http open eucalyptus com Appistry Inc Cloud Platforms vs Cloud Infrastructure White Paper 2009 Hayes Cloud computing Communications of the ACM 51 9 11 2008 P T Jaeger J Lin J Grimes and S N Simmons Where is the cloud Geography economics environment and jurisdiction in cloud computing First Monday 14 4 5 2009 VMWare Inc VMware vSphere the First Cloud Operating White Paper 2009 Platform Computing Platform ISF Datasheet White Paper 2009 40 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 INTRODUCTION TO CLOUD COMPUTING M D de Assuncao A di Costanzo and R Buyya Evaluating the cost benefit of using cloud computing to extend the capacity of clusters in Proceedings of the 18th ACM International Symposium on High Performance Distributed Computing HPDC 2009 Munich Germany 2009 141 150 D Amrhein Websphere Journal ttp websphere sys con com node 1029500 22 4 2010 Libvirt The Virtualization API Terminology and Goals http libvirt org goals html 22 4 2010 A Singh M Korupolu and D Mohapatra Server storage virtualization Inte gration and load balancing in data centers in Procee
36. ere are countless other definitions there seems to be common characteristics between the most notable ones listed above which a cloud should have 1 pay per use no ongoing commitment utility prices 1 elastic capacity and the illusion of infinite resources iii self service interface and iv resources that are abstracted or virtualised In addition to raw computing and storage cloud computing providers usually offer a broad range of software services They also include APIs and development tools that allow developers to build seamlessly scalable applica tions upon their services The ultimate goal is allowing customers to run their everyday IT infrastructure in the cloud A lot of hype has surrounded the cloud computing area in its infancy often considered the most significant switch in the IT world since the advent of the 1 2 ROOTS OF CLOUD COMPUTING 5 Internet 8 In midst of such hype a great deal of confusion arises when trying to define what cloud computing is and which computing infrastructures can be termed as clouds Indeed the long held dream of delivering computing as a utility has been realized with the advent of cloud computing 5 However over the years several technologies have matured and significantly contributed to make cloud computing viable In this direction this introduction tracks the roots of cloud computing by surveying the main technological advancements that significantly contributed to t
37. es the required features e g accounting and billing to offer multi tenant pay as you go services Cloud development environments are built on top of infrastructure services to offer application development and deployment capabilities in this level various programming models libraries APIs and mashup editors enable the creation of a range of business Web and scientific applications Once deployed in the cloud these applications can be consumed by end users 1 3 1 Infrastructure as a Service Offering virtualized resources computation storage and communication on demand is known as Infrastructure as a Service IaaS 7 A cloud infrastructure 14 INTRODUCTION TO CLOUD COMPUTING Service Main Access amp Servi Class Management Tool conten J mii Dra Ve Cloud Applications D D Web Browser Social networks Office suites CRM SaaS Video processing ae gt Fe Cloud Cloud Platform Development p R Environment Programming languages Frameworks Mashups editors Structured data X JSN A 7 gt Virtual Cloud Infrastructure Infrastructure iad Manager aa Storage 17 irewall Load Balancer JSN JSN 7 FIGURE 1 3 The cloud computing stack enables on demand provisioning of servers running several choices of operating systems and a customized software stack Infrastructure services are considered to be the bottom layer of cloud computing systems 39 Ama
38. he advent of this emerging field It also explains concepts and developments by categorizing and comparing the most relevant R amp D efforts in cloud computing especially public clouds management tools and development frameworks The most significant practical cloud computing realizations are listed with special focus on architectural aspects and innovative technical features 1 2 ROOTS OF CLOUD COMPUTING We can track the roots of clouds computing by observing the advancement of several technologies especially in hardware virtualization multi core chips Internet technologies Web services service oriented architectures Web 2 0 distributed computing clusters grids and systems management autonomic computing data center automation Figure 1 1 shows the convergence of technology fields that significantly advanced and contributed to the advent of cloud computing Some of these technologies have been tagged as hype in their early stages of development however they later received significant attention from academia and were sanctioned by major industry players Consequently a specification and standardization process followed leading to maturity and wide adoption The emergence of cloud computing itself is closely linked to the maturity of such technologies We present a closer look at the technol ogies that form the base of cloud computing with the aim of providing a clearer picture of the cloud ecosystem as a whole 1 2 1 From
39. hem on the cloud platform Each model aims at efficiently solving a particular problem In the cloud computing domain the most common activities that require specialized models are processing of large dataset in clusters of computers MapReduce model development of request based Web services and applica tions definition and orchestration of business processes in the form of work flows Workflow model and high performance distributed execution of various computational tasks For user convenience PaaS providers usually support multiple programming languages Most commonly used languages in platforms include Python and Java e g Google AppEngine NET languages e g Microsoft Azure and Ruby e g Heroku Force com has devised its own programming language Apex and an Excel like query language which provide higher levels of abstraction to key platform functionalities A variety of software frameworks are usually made available to PaaS developers depending on application focus Providers that focus on Web and enterprise application hosting offer popular frameworks such as Ruby on Rails Spring Java EE and NET Persistence Options A persistence layer is essential to allow applications to record their state and recover it in case of crashes as well as to store user data 32 INTRODUCTION TO CLOUD COMPUTING Traditionally Web and enterprise application developers have chosen rela tional databases as the preferred persistence me
40. iances eases software customization configuration and patching and improves portability Most commonly an appliance is shaped as a VM disk image associated with hardware requirements and it can be readily deployed in a hypervisor On line marketplaces have been set up to allow the exchange of ready made appliances containing popular operating systems and useful software combina tions both commercial and open source Most notably the VMWare virtual appliance marketplace allows users to deploy appliances on VMWare hypervi sors or on partners public clouds 30 and Amazon allows developers to share specialized Amazon Machine Images AMI and monetize their usage on Amazon EC2 31 In a multitude of hypervisors where each one supports a different VM image format and the formats are incompatible with one another a great deal of interoperability issues arises For instance Amazon has its Amazon machine image AMI format made popular on the Amazon EC2 public cloud Other formats are used by Citrix XenServer several Linux distributions that ship with KVM Microsoft Hyper V and VMware ESX In order to facilitate packing and distribution of software to be run on VMs several vendors including VMware IBM Citrix Cisco Microsoft Dell and HP have devised the Open Virtualization Format OVF It aims at being open secure portable efficient and extensible 32 An OVF package consists of a file or set of files describing the VM hardw
41. ing Interoperability Forum CCIF was formed by organizations such as Intel Sun and Cisco in order to enable a global cloud computing ecosystem whereby organizations are able to seamlessly work together for the purposes for wider industry adoption of cloud computing technology The development of the Unified Cloud Interface UCI by CCIF aims at creating a standard programmatic point of access to an entire cloud infrastructure In the hardware virtualization sphere the Open Virtual Format OVF aims at facilitating packing and distribution of software to be run on VMs so that virtual appliances can be made portable that is seamlessly run on hypervisor of different vendors 36 INTRODUCTION TO CLOUD COMPUTING 1 8 3 Availability Fault Tolerance and Disaster Recovery It is expected that users will have certain expectations about the service level to be provided once their applications are moved to the cloud These expectations include availability of the service its overall performance and what measures are to be taken when something goes wrong in the system or its components In summary users seek for a warranty before they can comfortably move their business to the cloud SLAs which include QoS requirements must be ideally set up between customers and cloud computing providers to act as warranty An SLA specifies the details of the service to be provided including availability and performance guarantees Additionally metrics mu
42. is typically exploited by a pay per use model in which guarantees are offered by the Infrastructure Provider by means of customized Service Level Agreements A recent McKinsey and Co report 4 claims that Clouds are hardware based services offering compute network and storage capacity where Hardware management is highly abstracted from the buyer buyers incur infrastructure costs as variable OPEX and infrastructure capacity is highly elastic A report from the University of California Berkeley 5 summarized the key characteristics of cloud computing as 1 the illusion of infinite computing resources 2 the elimination of an up front commitment by cloud users and 3 the ability to pay for use as needed The National Institute of Standards and Technology NIST 6 charac terizes cloud computing as a pay per use model for enabling available convenient on demand network access to a shared pool of configurable computing resources e g networks servers storage applications services that can be rapidly provisioned and released with minimal management effort or service provider interaction In a more generic definition Armbrust et al 5 define cloud as the data center hardware and software that provide services Similarly Sotomayor et al 7 point out that cloud is more often used to refer to the IT infrastructure deployed on an Infrastructure as a Service provider data center While th
43. itiative has contributed to define the four properties of autonomic systems self configuration self optimization self healing and self protection IBM has also suggested a reference model for autonomic control loops of autonomic managers called MAPE K Monitor Analyze Plan Execute Knowledge 34 35 The large data centers of cloud computing providers must be managed in an efficient way In this sense the concepts of autonomic computing inspire software technologies for data center automation which may perform tasks such as management of service levels of running applications management of data center capacity proactive disaster recovery and automation of VM provisioning 36 1 3 LAYERS AND TYPES OF CLOUDS Cloud computing services are divided into three classes according to the abstraction level of the capability provided and the service model of providers namely 1 Infrastructure as a Service 2 Platform Service and 3 Software as a Service 6 Figure 1 3 depicts the layered organization of the cloud stack from physical infrastructure to applications These abstraction levels can also be viewed as a layered architecture where services of a higher layer can be composed from services of the underlying layer 37 The reference model of Buyya et al 38 explains the role of each layer in an integrated architecture A core middleware manages physical resources and the VMs deployed on top of them in addition it provid
44. le system directly you must use the Google Datastore or open a socket or access another host directly you must use Google URL fetch service A Java application cannot create a new Thread either Microsoft Azure Microsoft Azure Cloud Services offers developers a hosted NET Stack C VB Net ASP NET In addition a Java amp Ruby SDK for Services is also available The Azure system consists of a number of elements The Windows Azure Fabric Controller provides auto scaling and reliability and it manages memory resources and load balancing The NET Service Bus registers and connects applications together The NET Access Control identity providers include enterprise directories and Windows LivelID Finally the NET Workflow allows construction and execution of workflow instances Force com In conjunction with the Salesforce com service the Force com PaaS allows developers to create add on functionality that integrates into main Salesforce CRM SaaS application Force com offers developers two approaches to create applications that can be deployed on its SaaS plaform a hosted Apex or Visualforce application Apex is a proprietary Java like language that can be used to create Salesforce applications Visualforce is an XML like syntax for building UIs in HTML AJAX or Flex to overlay over the Salesforce hosted CRM system An application store called AppExchange is also provided which offers a paid amp free application directory
45. ller packaged as a virtual appliance Web portal interface dynamic resource allocation advance reservation of capacity high availability VMWare vSphere and vCloud vSphere is VMware s suite of tools aimed at transforming IT infrastructures into private clouds 36 43 It distinguishes from other VI managers as one of the most feature rich due to the company s several offerings in all levels the architecture In the vSphere architecture servers run on the ESXi platform A separate server runs vCenter Server which centralizes control over the entire virtual infrastructure Through the vSphere Client software administrators connect to vCenter Server to perform various tasks The Distributed Resource Scheduler DRS makes allocation decisions based on predefined rules and policies It continuously monitors the amount of resources available to VMs and if necessary makes allocation changes to meet VM requirements In the storage virtualization realm vStorage VMFS is a cluster file system to provide aggregate several disks in a single volume is especially optimized to store VM images and virtual disks It supports storage equipment that use Fibre Channel or iSCSI SAN In its basic setup vSphere is essentially a private administration suite Self service VM provisioning to end users is provided via the vCloud API which 26 INTRODUCTION TO CLOUD COMPUTING interfaces with vCenter Server In this configuration vSphere can be used
46. manageability and higher reliability More recently with the adoption of virtualization on a broad range of server and client systems researchers and practitioners have been emphasizing three basic capabilities regarding Virtual Machine 1 b a Virtual Machine 2 Virtual Machine N N User software User software User software Email Server Facebook App AppA App X Ruby on Java Rails Data Web base Server Cer L Windows JJ Linux JJ N Guest OS Virtual Machine Monitor Hypervisor Hardware FIGURE 1 2 A hardware virtualized server hosting three virtual machines each one running distinct operating system and user level software stack 1 2 ROOTS OF CLOUD COMPUTING 11 management of workload in a virtualized system namely isolation consolida tion and migration 23 Workload isolation is achieved since all program instructions are fully confined inside a VM which leads to improvements in security Better reliability is also achieved because software failures inside one VM do not affect others 22 Moreover better performance control is attained since execution of one VM should not affect the performance of another VM 23 The consolidation of several individual and heterogeneous workloads onto a single physical platform leads to better system utilization This pra
47. ms and v different billing methods and period e g prepaid vs post paid hourly vs monthly Geographic Presence To improve availability and responsiveness a provi der of worldwide services would typically build several data centers distributed around the world For example Amazon Web Services presents the concept of availability zones and regions for its EC2 service Availability zones are distinct locations that are engineered to be insulated from failures in other availability zones and provide inexpensive low latency network connectivity to other availability zones in the same region Regions in turn are geographi cally dispersed and will be in separate geographic areas or countries 70 User Interfaces and Access to Servers Ideally a public IaaS provider must provide multiple access means to its cloud thus catering for various users and their preferences Different types of user interfaces UI provide different levels of abstraction the most common being graphical user interfaces GUI command line tools CLI and Web service WS APIs 1 6 INFRASTRUCTURE AS A SERVICE PROVIDERS 27 GUIs are preferred by end users who need to launch customize and monitor a few virtual servers and do not necessary need to repeat the process several times On the other hand CLIs offer more flexibility and the possibility of automating repetitive tasks via scripts e g start and shutdown a number of virtual serve
48. nce that rely on redundancy of VMs are implemented In this style redundant and synchro nized VMs running or in standby are kept in a secondary physical server The HA solution monitors failures of system components such as servers VMs disks and network and ensures that a duplicate VM serves the application in case of failures 58 Data backup in clouds should take into account the high data volume involved in VM management Frequent backup of a large number of VMs each one with multiple virtual disks attached should be done with minimal interference in the systems performance In this sense some VI managers offer data protection mechanisms that perform incremental backups of VM images The backup workload is often assigned to proxies thus offloading production server and reducing network overhead 59 1 5 CLOUD INFRASTRUCTURE MANAGEMENT 21 1 5 2 Case Studies In this section we describe the main features of the most popular VI managers available Only the most prominent and distinguishing features of each tool are discussed in detail A detailed side by side feature comparison of VI managers is presented in Table 1 1 Apache VCL The Virtual Computing Lab 60 61 project has been incepted in 2004 by researchers at the North Carolina State University as a way to provide customized environments to computer lab users The software compo nents that support NCSU s initiative have been released as open source and incorporated by the
49. ness of energy consumption in data centers has encouraged the practice of dynamic consolidating VMs in a fewer number of servers In cloud infrastructures where applications have variable and dynamic needs capacity management and demand predic tion are especially complicated This fact triggers the need for dynamic resource allocation aiming at obtaining a timely match of supply and demand 51 Energy consumption reduction and better management of SLAs can be achieved by dynamically remapping VMs to physical machines at regular intervals Machines that are not assigned any VM can be turned off or put on a low power state In the same fashion overheating can be avoided by moving load away from hotspots 52 A number of VI managers include a dynamic resource allocation feature that continuously monitors utilization across resource pools and reallocates avail able resources among VMs according to application needs 20 INTRODUCTION TO CLOUD COMPUTING Virtual Clusters Several VI managers can holistically manage groups of VMs This feature is useful for provisioning computing virtual clusters on demand and interconnected VMs for multi tier Internet applications 53 Reservation and Negotiation Mechanism When users request computa tional resources to available at a specific time requests are termed advance reservations AR in contrast to best effort requests when users request resources whenever available 54 To support complex requests
50. ng Citrix XenServer and Microsoft Hyper V 64 By providing several access interfaces it facilitates both human and programmatic interaction with the controller Automation of tasks is also aided by a workflow orchestration mechanism In summary Citrix Essentials provides the following features Windows based controller GUI CLI Web portal and XML RPC interfaces support for XenServer and Hyper V hypervisors Citrix Storage Link storage virtuali zation virtual networks dynamic resource allocation three level high avail ability 1 recovery by VM restart recovery by activating paused duplicate VM and running duplicate VM continuously 58 data protection with Citrix Consolidated Backup Enomaly ECP The Enomaly Elastic Computing Platform in its most complete edition offers most features a service provider needs to build an IaaS cloud Most notably ECP Service Provider Edition offers a Web based customer dashboard that allows users to fully control the life cycle of VMs Usage accounting is performed in real time and can be viewed by users Similar to the functionality of virtual appliance marketplaces ECP allows providers and users to package and exchange applications In summary Enomaly ECP provides the following features Linux based controller Web portal and Web services REST interfaces Xen back end interface to the Amazon EC2 public cloud virtual networks virtual clusters ElasticValet Eucalyptus The Eucalyp
51. o be managed in various VM management activities Such data amount is a result of particular abilities of virtual machines including the ability of traveling through space 1 migration and time 1 checkpointing and rewinding 74 operations that may be required in load balancing backup and recovery scenarios In addition dynamic provisioning of new VMs and replicating existing VMs require efficient mechanisms to make VM block storage devices e g image files quickly available at selected hosts Data centers consumer large amounts of electricity According to a data published by HP 4 100 server racks can consume 1 3 MW of power and another 1 3 MW are required by the cooling system thus costing USD 2 6 million per REFERENCES 37 year Besides the monetary cost data centers significantly impact the environ ment in terms of CO emissions from the cooling systems 52 In addition to optimize application performance dynamic resource manage ment can also improve utilization and consequently minimize energy consump tion in data centers This can be done by judiciously consolidating workload onto smaller number of servers and turning off idle resources 1 9 SUMMARY Cloud computing is a new computing paradigm that offers a huge amount of compute and storage resources to the masses Individuals e g scientists and enterprises e g startup companies have access to these resources paying a small amount of money
52. o old electricity generation stations which used to power individual factories computing servers and desktop computers in a modern organization are often underutilized since IT infrastructure is configured to handle theore tical demand peaks In addition in the early stages of electricity generation electric current could not travel long distances without significant voltage losses However new paradigms emerged culminating on transmission systems able to make electricity available hundreds of kilometers far off from where it is generated Likewise the advent of increasingly fast fiber optics networks has relit the fire and new technologies for enabling sharing of computing power over great distances have appeared These facts reveal the potential of delivering computing services with the speed and reliability that businesses enjoy with their local machines The benefits of economies of scale and high utilization allow providers to offer computing services for a fraction of what it costs for a typical company that generates its own computing power 8 1 2 2 SOA Web Services Web 2 0 and Mashups The emergence of Web services WS open standards has significantly con tributed to advances in the domain of software integration 12 Web services can glue together applications running on different messaging product plat forms enabling information from one application to be made available to others and enabling internal applications to be ma
53. ophisticated on demand computing services initially offered by commercial providers such as Amazon Google and Microsoft It denotes a model on which a computing infrastructure is viewed as a cloud from which businesses and individuals access applications from anywhere in the world on demand 2 The main principle behind this model is offering computing storage and software as a service Cloud Computing Principles and Paradigms Edited by Rajkumar Buyya James Broberg and Andrzej Goscinski Copyright 2011 John Wiley amp Sons Inc 4 INTRODUCTION TO CLOUD COMPUTING Many practitioners in the commercial and academic spheres have attempted to define exactly what cloud computing is and what unique characteristics it presents Buyya et al 2 have defined it as follows Cloud is a parallel and distributed computing system consisting of a collection of inter connected and virtualised computers that are dynamically provisioned and presented as one or more unified computing resources based on service level agreements SLA established through negotiation between the service provider and consumers Vaquero et al 3 have stated clouds are a large pool of easily usable and accessible virtualized resources such as hardware development platforms and or services These resources can be dynamically reconfigured to adjust to a variable load scale allowing also for an optimum resource utilization This pool of resources
54. project and has served as a base to other virtualization products both commercial and open source It has pioneered the para virtualization concept on which the guest operating system by means of a specialized kernel can interact with the hypervisor thus significantly improving performance In addition to an open source distribu tion 25 Xen currently forms the base of commercial hypervisors of a number of vendors most notably Citrix XenServer 26 and Oracle VM 27 KVM The kernel based virtual machine KVM is a Linux virtualization subsystem Is has been part of the mainline Linux kernel since version 2 6 20 thus being natively supported by several distributions In addition activities such as memory management and scheduling are carried out by existing kernel 12 INTRODUCTION TO CLOUD COMPUTING features thus making KVM simpler and smaller than hypervisors that take control of the entire machine 28 KVM leverages hardware assisted virtualization which improves perfor mance and allows it to support unmodified guest operating systems 29 currently it supports several versions of Windows Linux and UNIX 28 1 2 6 Virtual Appliances and the Open Virtualization Format An application combined with the environment needed to run it operating system libraries compilers databases application containers and so forth is referred to as a virtual appliance Packaging application environments in the shape of virtual appl
55. r of virtual servers is increased by automatic scaling incoming traffic must be automatically distributed among the available servers This activity enables applications to promptly respond to traffic increase while also achieving greater fault tolerance Service Level Agreement Service level agreements SLAs are offered by IaaS providers to express their commitment to delivery of a certain QoS To customers it serves as a warranty An SLA usually include availability and performance guarantees Additionally metrics must be agreed upon by all parties as well as penalties for violating these expectations Most IaaS providers focus their SLA terms on availability guarantees specifying the minimum percentage of time the system will be available during a certain period For instance Amazon EC2 states that if the annual uptime Percentage for a customer drops below 99 95 for the service year that customer is eligible to receive a service credit equal to 10 of their bill 3 http aws amazon com ec2 sla 28 INTRODUCTION TO CLOUD COMPUTING Hypervisor and Operating System Choice Traditionally IaaS offerings have been based on heavily customized open source Xen deployments IaaS providers needed expertise in Linux networking virtualization metering resource management and many other low level aspects to successfully deploy and maintain their cloud offerings More recently there has been an emergence of turnkey IaaS platforms such as
56. rm com Products platform vm orchestrator 22 4 2010 Amazon Inc Amazon Web Services http www amazon com 22 4 2010 F Chang et al Bigtable A distributed storage system for structured data in Proceedings of the 7th USENIX Symposium on Operating Systems Design and Implementation OSDI 06 2006 205 218 Vecchiola X Chu and Buyya Aneka A software platform for NET based cloud computing in High Speed and Large Scale Scientific Computing W Gentzsch L Grandinetti and G Joubert eds IOS Press Amsterdam Nether lands 2009 267 295 W Voorsluys J Broberg S Venugopal and R Buyya Cost of virtual machine live migration in clouds A performance evaluation in Proceedings 151 International Conference on Cloud Computing Beijing 2009 pp 254 265 D T Meyer et al Parallax Virtual disks for virtual machines in Proceedings of the 3rd ACM SIGOPS EuroSys European Conference on Computer Systems 2008 pp 41 54
57. rs at regular intervals WS APIs offer programmatic access to a cloud using standard HTTP requests thus allowing complex services to be built on top of IaaS clouds Advance Reservation of Capacity Advance reservations allow users to request for an IaaS provider to reserve resources for a specific time frame in the future thus ensuring that cloud resources will be available at that time However most clouds only support best effort requests that is users requests are server whenever resources are available 54 Amazon Reserved Instances is a form of advance reservation of capacity allowing users to pay a fixed amount of money in advance to guarantee resource availability at anytime during an agreed period and then paying a discounted hourly rate when resources are in use However only long periods of 1 to 3 years are offered therefore users cannot express their reservations in finer granularities for example hours or days Automatic Scaling and Load Balancing As mentioned earlier in this chapter elasticity is a key characteristic of the cloud computing model Applications often need to scale up and down to meet varying load conditions Automatic scaling is a highly desirable feature of IaaS clouds It allow users to set conditions for when they want their applications to scale up and down based on application specific metrics such as transactions per second number of simultaneous users request latency and so forth When the numbe
58. ructure required to run it Once the application is stopped AppLogic tears down the infrastructure built for it 63 AppLogic offers dynamic appliances to add functionality such as Disaster Recovery and Power optimization to applications 62 The key differential of this approach is that additional functionalities are implemented as another pluggable appliance instead of being added as a core functionality of the VI manager In summary 3tera AppLogic provides the following features Linux based controller CLI and GUI interfaces Xen backend Global Volume Store GVS storage virtualization virtual networks virtual clusters dynamic resource allocation high availability and data protection SAWA 8 103 XSA SM 9204 5 Sok IRMA A IWMWA IIEMWA IND ITO nurg IPM WA ON Sok SOK Sok 9 puod nuq Awpudoig OWA 59014196 osudiajugq dH 481 regpuy PUN SOX Sox soX 0D WAI TOA 1 4 21204 ON ON WAX xnu TA erer ON ON Sok ON ON ON ON SM Hoq TA PIA s soH enef 110 SOX SOX SOX TO vozeuy WAX
59. s allowing several internal components to be replaced and also eases the integration with other systems In summary Nimbus provides the following features Linux based control ler EC2 compatible SOAP and WSRF interfaces Xen and KVM backend and a Pilot program to spawn VMs through an LRM interface to the Amazon EC2 public cloud virtual networks one click virtual clusters OpenNebula OpenNebula is one of the most feature rich open source VI managers It was initially conceived to manage local virtual infrastructure but has also included remote interfaces that make it viable to build public clouds Altogether four programming APIs are available XML RPC and libvirt 47 for local interaction a subset of EC2 Query APIs and the OpenNebula Cloud API OCA for public access 7 65 Its architecture is modular encompassing several specialized pluggable components The Core module orchestrates physical servers and their hypervi sors storage nodes and network fabric Management operations are performed through pluggable Drivers which interact with APIs of hypervisors storage and network technologies and public clouds The Scheduler module which is in charge of assigning pending VM requests to physical hosts offers dynamic resource allocation features Administrators can choose between different scheduling objectives such as packing VMs in fewer hosts or keeping the load balanced Via integration with the Haizea lease scheduler 66 Open
60. s free hardware load balancing auto scaling capabilities and persistent storage features that typically add an additional cost for most other IaaS providers 1 7 PLATFORM AS A SERVICE PROVIDERS 31 Rackspace Cloud Servers Rackspace Cloud Servers is an IaaS solution that provides fixed size instances in the cloud Cloud Servers offers a range of Linux based pre made images A user can request different sized images where the size is measured by requested RAM not CPU Like GoGrid Cloud Servers also offers hybrid approach where dedicated and cloud server infrastructures can be combined to take the best aspects of both styles of hosting as required Cloud Servers as part of its default offering enables fixed static IP addresses persistent storage and load balancing via A DNS at no additional cost 1 7 PLATFORM AS A SERVICE PROVIDERS Public Platform as a Service providers commonly offer a development and deployment environment that allow users to create and run their applications with little or no concern to low level details of the platform In addition specific programming languages and frameworks are made available in the platform as well as other services such as persistent data storage and in memory caches 1 7 1 Features Programming Models Languages and Frameworks Programming mod els made available by IaaS providers define how users can express their applications using higher levels of abstraction and efficiently run t
61. st be agreed upon by all parties and penalties for violating the expectations must also be approved 1 8 4 Resource Management and Energy Efficiency One important challenge faced by providers of cloud computing services is the efficient management of virtualized resource pools Physical resources such as CPU cores disk space and network bandwidth must be sliced and shared among virtual machines running potentially heterogeneous workloads The multi dimensional nature of virtual machines complicates the activity of finding a good mapping of VMs onto available physical hosts while maximizing user utility Dimensions to be considered include number of CPUs amount of memory size of virtual disks and network bandwidth Dynamic VM mapping policies may leverage the ability to suspend migrate and resume VMs as an easy way of preempting low priority allocations in favor of higher priority ones Migration of VMs also brings additional challenges such as detecting when to initiate a migration which VM to migrate and where to migrate In addition policies may take advantage of live migration of virtual machines to relocate data center load without significantly disrupting running services In this case an additional concern is the trade off between the negative impact of a live migration on the performance and stability of a service and the benefits to be achieved with that migration 73 Another challenge concerns the outstanding amount of data t
62. table computing needs Providers of IT services achieve better operational costs hardware and software infrastructures are built to provide multiple solutions and serve many users thus increasing efficiency and ultimately leading to faster return on investment as well as lower total cost of ownership TCO 10 Several technologies have in some way aimed at turning the utility comput ing concept into reality In the 1970s companies who offered common data processing tasks such as payroll automation operated time shared mainframes as utilities which could serve dozens of applications and often operated close to 100 of their capacity In fact mainframes had to operate at very high utilization rates simply because they were very expensive and costs should be justified by efficient usage 8 The mainframe era collapsed with the advent of fast and inexpensive microprocessors and IT data centers moved to collections of commodity servers Apart from its clear advantages this new model inevitably led to isolation of workload into dedicated servers mainly due to incompatibilities 1 2 ROOTS OF CLOUD COMPUTING 7 between software stacks and operating systems 11 In addition the unavail ability of efficient computer networks meant that IT infrastructure should be hosted in proximity to where it would be consumed Altogether these facts have prevented the utility computing reality of taking place on modern computer systems Similar t
63. tant messaging service XMPP an image manipulation service and integration with Google Accounts authentication service 1 3 3 Software as a Service Applications reside on the top of the cloud stack Services provided by this layer can be accessed by end users through Web portals Therefore consumers are increasingly shifting from locally installed computer programs to on line software services that offer the same functionally Traditional desktop applica tions such as word processing and spreadsheet can now be accessed as a service in the Web This model of delivering applications known as Software as a Service SaaS alleviates the burden of software maintenance for customers and simplifies development and testing for providers 37 41 Salesforce com which relies on the SaaS model offers business productivity applications CRM that reside completely on their servers allowing costumers to customize and access applications on demand 1 3 4 Deployment Models Although cloud computing has emerged mainly from the appearance of public computing utilities other deployment models with variations in physical location and distribution have been adopted In this sense regardless of its service class a cloud can be classified as public private community or hybrid 6 based on model of deployment as shown in Figure 1 4 4 Hybria Mixed Clouds Cloud computing Mixed usage of model run private and public within a company s own
64. tems Journal of Computer Science and Technology 21 513 520 2006 R Buyya and S Venugopal Market oriented computing and global Grids An introduction in Market Oriented Grid and Utility Computing R Buyya and K Bubendorfer eds John Wiley amp Sons Hoboken NJ 2009 pp 24 44 K Keahey I Foster T Freeman and X Zhang Virtual workspaces Achieving quality of service and quality of life in the grid Scientific Programming 13 4 265 275 2005 R P Goldberg Survey of virtual machine research IEEE Computer 7 6 34 45 1974 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 REFERENCES 39 Uhlig et al Intel virtualization technology IEEE Computer 38 5 48 56 2005 P Barham et al Xen and the art of virtualization in Proceedings of 19th ACM Symposium on Operation Systems Principles New York 2003 164 177 VMWare Inc VMWare hittp www vmware com 22 4 2010 Xen org Community ttp www xen org 22 4 2010 Citrix Systems Inc XenServer http www citrix com XenServer 22 4 2010 Oracle Corp Oracle VM http www oracle com technology products vm 24 4 2010 KVM Project Kernel based virtual machine http www linux kvm org 22 4 2010 A Kivity Y Kamay D Laor U Lublin and A Liguori KVM The Linux virtual machine monitor in Proceedings of the Linux Symposium Ottawa Canada 2007 p 225 V
65. thod These databases offer fast and reliable structured data storage and transaction processing but may lack scalability to handle several petabytes of data stored in commodity computers 71 In the cloud computing domain distributed storage technologies have emerged which seek to be robust and highly scalable at the expense of relational structure and convenient query languages For example Amazon SimpleDB and Google AppEngine datastore offer schema less automatically indexed database services 70 Data queries can be performed only on individual tables that is join operations are unsupported for the sake of scalability 1 7 2 Case Studies In this section we describe the main features of some Platform as Service PaaS offerings A more detailed side by side feature comparison of VI managers is presented in Table 1 3 Aneka 72 is a NET based service oriented resource management and development platform Each server in an Aneka deployment dubbed Aneka cloud node hosts the Aneka container which provides the base infrastructure that consists of services for persistence security authorization authentication and auditing and communication message handling and dispatching Cloud nodes can be either physical server virtual machines XenServer and VMware are supported and instances rented from Amazon EC2 The Aneka container can also host any number of optional services that can be added by developers to augment
66. tting up virtual disks for VMs These basic features pretty much define whether a tool can be used in practical cloud deployments or not On the other hand only a handful of software present advanced features e g high availability which allow them to be used in large scale production clouds 1 5 1 Features We now present a list of both basic and advanced features that are usually available in VIMs Virtualization Support The multi tenancy aspect of clouds requires multiple customers with disparate requirements to be served by a single hardware infrastructure Virtualized resources CPUs memory etc can be sized and resized with certain flexibility These features make hardware virtualization the ideal technology to create a virtual infrastructure that partitions a data center among multiple tenants Self Service On Demand Resource Provisioning Self service access to resources has been perceived as one the most attractive features of clouds This feature enables users to directly obtain services from clouds such as spawning the creation of a server and tailoring its software configurations and security policies without interacting with a human system administrator This cap ability eliminates the need for more time consuming labor intensive human driven procurement processes familiar to many in IT 46 Therefore exposing a self service interface through which users can easily interact with the system is a highly desira
67. tus 39 framework was one of the first open source projects to focus on building IaaS clouds It has been developed with the intent of providing an open source implementation nearly identical in functionality to Amazon Web Services APIs Therefore users can interact with a Eucalyptus cloud using the same tools they use to access Amazon 2 It also distinguishes itself from other tools because it provides a storage cloud API emulating the Amazon 53 API for storing general user data and VM images In summary Eucalyptus provides the following features Linux based con troller with administration Web portal EC2 compatible SOAP Query and 53 compatible SOAP REST CLI and Web portal interfaces Xen KVM and VMWare backends Amazon EBS compatible virtual storage devices interface to the Amazon EC2 public cloud virtual networks Nimbus3 The Nimbus toolkit 20 is built on top of the Globus framework Nimbus provides most features in common with other open source VI managers such as an EC2 compatible front end API support to Xen and a backend interface to Amazon EC2 However it distinguishes from others by 24 INTRODUCTION TO CLOUD COMPUTING providing a Globus Web Services Resource Framework WSRF interface It also provides a backend service named Pilot which spawns VMs on clusters managed by a local resource manager LRM such as PBS and SGE Nimbus core was engineered around the Spring framework to be easily extensible thu
68. tware load balancing is available as an accelerator in addition to hardware load balancers A notable feature of Joyent s virtual servers is automatic vertical scaling of CPU cores which means a virtual server can make use of additional CPUs automatically up to the maximum number of cores available in the physical host In summary the Joyent public cloud offers the following features multiple geographic locations in the United States Web based user interface access to virtual server via SSH and Web based administration tool 100 availability SLA per month pricing OS level virtualization Solaris containers Open Solaris operating systems automatic scaling vertical GoGrid GoGrid like many other IaaS providers allows its customers to utilize a range of pre made Windows and Linux images in a range of fixed instance sizes GoGrid also offers value added stacks on top for applications such as high volume Web serving e Commerce and database stores It offers some notable features such as a hybrid hosting facility which combines traditional dedicated hosts with auto scaling cloud server infrastruc ture In this approach users can take advantage of dedicated hosting which may be required due to specific performance security or legal compliance reasons and combine it with on demand cloud infrastructure as appropriate taking the benefits of each style of computing As part of its core IaaS offerings GoGrid also provide
69. ver secure authentication services based on freeIPA and provisioning services to manage VM image and their transfer to the managed nodes Each managed node libvirt which interfaces with the hypervisor In summary oVirt provides the following features Fedora Linux based controller packaged as a virtual appliance Web portal interface KVM backend Platform ISF Infrastructure Sharing Facility ISF is the VI manager offering from Platform Computing 68 The company mainly through its LSF family of products has been serving the HPC market for several years ISF s architecture is divided into three layers The top most Service Delivery layer includes the user interfaces 1 self service portal and APIs the Allocation Engine provides reservation and allocation policies and the bottom layer Resource Integrations provides adapters to interact with hypervisors provisioning tools and other systems 1 external public clouds The Allocation Engine also provides policies to address several objectives such as minimizing energy consumption reducing impact of failures and maximizing application performance 44 ISF is built upon Platform s VM Orchestrator which as a standalone product aims at speeding up delivery of VMs to end users It also provides high availability by restarting VMs when hosts fail and duplicating the VM that hosts the VMO controller 69 In summary ISF provides the following features Linux based contro
70. vice Interface to Public Clouds Researchers have perceived that extending the capacity of a local in house computing infrastructure by borrowing resources from public clouds is advantageous In this fashion institutions can make good use of their available resources and in case of spikes in demand extra load can be offloaded to rented resources 45 A VI manager can be used in a hybrid cloud setup if it offers a driver to manage the life cycle of virtualized resources obtained from external cloud providers To the applications the use of leased resources must ideally be transparent Virtual Networking Virtual networks allow creating an isolated network on top of a physical infrastructure independently from physical topology and locations 49 A virtual LAN VLAN allows isolating traffic that shares a switched network allowing VMs to be grouped into the same broadcast domain Additionally a VLAN can be configured to block traffic originated from VMs from other networks Similarly the VPN virtual private network concept is used to describe a secure and private overlay network on top of a public network most commonly the public Internet 50 Support for creating and configuring virtual networks to group VMs placed throughout a data center is provided by most VI managers Additionally VI managers that interface with public clouds often support secure VPNs connecting local and remote VMs Dynamic Resource Allocation Increased aware
71. zon Web Services mainly offers IaaS which in the case of its EC2 service means offering VMs with a software stack that can be customized similar to how an ordinary physical server would be customized Users are given privileges to perform numerous activities to the server such as starting and stopping it customizing it by installing software packages attaching virtual disks to it and configuring access permissions and firewalls rules 1 3 2 Platform as a Service In addition to infrastructure oriented clouds that provide raw computing and storage services another approach is to offer a higher level of abstraction to make a cloud easily programmable known as Platform as a Service PaaS A cloud platform offers an environment on which developers create and deploy applications and do not necessarily need to know how many processors or how much memory that applications will be using In addition multiple program ming models and specialized services e g data access authentication and payments are offered as building blocks to new applications 40 Google AppEngine an example of Platform as a Service offers a scalable environment for developing and hosting Web applications which should be written in specific programming languages such as Python or Java and use the services own proprietary structured object data store Building blocks 1 3 LAYERS AND TYPES OF CLOUDS 15 include an in memory object cache memcache mail service ins

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