Lab Validation Report

Lab Validation Report Citrix XenServer 6.0 Server Virtualization for Enterprise Applications By Mike Leone and Vinny Choinski January 2012

Lab Validation: Citrix XenServer 6.0 2 Contents Introduction... 3 Background... 3 Citrix XenServer... 4 ESG Lab Validation... 5 ESG Lab Test Bed... 5 Conversion... 6 Performance... 7 Manageability and Optimization... 11 ESG Lab Validation Highlights... 14 Issues to Consider... 14 The Bigger Truth... 15 Appendix... 16 ESG Lab Reports The goal of ESG Lab reports is to educate IT professionals about emerging technologies and products in the storage, data management and information security industries. ESG Lab reports are not meant to replace the evaluation process that should be conducted before making purchasing decisions, but rather to provide insight into these emerging technologies. Our objective is to go over some of the more valuable feature/functions of products, show how they can be used to solve real customer problems and identify any areas needing improvement. ESG Lab's expert third-party perspective is based on our own hands-on testing as well as on interviews with customers who use these products in production environments. This ESG Lab report was sponsored by Citrix. All trademark names are property of their respective companies. Information contained in this publication has been obtained by sources The Enterprise Strategy Group (ESG) considers to be reliable but is not warranted by ESG. This publication may contain opinions of ESG, which are subject to change from time to time. This publication is copyrighted by The Enterprise Strategy Group, Inc. Any reproduction or redistribution of this publication, in whole or in part, whether in hard-copy format, electronically, or otherwise to persons not authorized to receive it, without the express consent of the Enterprise Strategy Group, Inc., is in violation of U.S. Copyright law and will be subject to an action for civil damages and, if applicable, criminal prosecution. Should you have any questions, please contact ESG Client Relations at (508) 482.0188.

Introduction Lab Validation: Citrix XenServer 6.0 3 This ESG Lab Validation Report presents hands-on evaluation and testing results of Citrix XenServer. Testing centered on virtualized server performance when compared to physical server performance with a focus on virtual server migration and application performance in a virtualized environment. ESG Lab also looked at the performance monitoring and optimization capabilities of XenServer, including the use of Citrix s dynamic memory allocation. Background Server virtualization has and will continue to have a major impact on IT organizations. According to ESG research, it is the top IT priority for organizations over the next 12-18 months (see Figure 1). Of the 611 senior IT professionals surveyed, 30% said their organization s most important priority was the increased usage of server virtualization. What s more, this is the third consecutive year in which server virtualization has topped the priorities list. 1 Organizations continue to realize the significant value server virtualization offers as they more effectively and efficiently utilize existing IT resources. Figure 1. Top IT Priorities Which of the following would you consider to be your organization s most important IT priorities over the next 12-18 months? (Percent of respondents, N=611, ten responses accepted) Increase use of server virtualization 30% Manage data growth Information security initiatives Major application deployments or upgrades Improve data backup and recovery Desktop virtualization Data center consolidation Business continuity/disaster recovery programs Large-scale desktop / laptop PC refresh Regulatory compliance initiatives 24% 24% 23% 22% 21% 21% 20% 19% 18% 0% 5% 10% 15% 20% 25% 30% 35% Source: Enterprise Strategy Group, 2011. 1 Source: ESG Research Report, 2011 IT Spending Intentions Survey, January 2011.

Lab Validation: Citrix XenServer 6.0 4 Citrix XenServer Citrix XenServer is a virtualized server platform built on the powerful, open-source Xen hypervisor. This enterpriseready and cloud-proven solution allows for the quick creation and efficient management of virtual infrastructures to positively impact an evolving data center. By enabling increased IT infrastructure agility and efficiency, XenServer allows for dynamic adjustment of VM resources as well as flexible VM placement within an infrastructure. Figure 2. Citrix XenServer XenServer is a full, virtual solution, helping companies achieve increased administrative efficiency through data center automation, business continuity through higher reliability, and the extension of an IT infrastructure by leveraging the cloud. Automation. XenServer consolidates server workloads to help optimize existing hardware utilization by reducing power, cooling, and management costs. The automation of key IT processes can also help save time and money by improving application service delivery for IT administrators. Adaptability. XenServer dynamically optimizes server workloads to increase performance and utilization. Adding new applications becomes easier and faster without sacrificing existing performance necessities and application requirements. Reliability. Application downtime or disruption is unacceptable for many businesses. Keeping an infrastructure up and running and protected from disaster is imperative for efficiency and productivity. With XenServer, virtual servers and physical hardware are separated and therefore easier to protect than in a physical environment, greatly reducing organization downtime. Cloud Readiness. IT infrastructure flexibility is becoming a requirement. This is especially true as more organizations move to the cloud to lower costs and increase IT service responsiveness. XenServer s flexibility allows for quick customizations to fit any business.

ESG Lab Validation Lab Validation: Citrix XenServer 6.0 5 ESG Lab performed hands-on evaluation and testing of XenServer at a Citrix s Bedford, MA facility. Testing was designed to demonstrate ease of physical to virtual server migration, the ability to support enterprise applications in a virtual environment, and the manageability and optimization of virtual machine performance. ESG Lab Test Bed ESG Lab focused its testing around physical and virtual application performance and manageability. The goal was to attain similar performance in a virtual environment when compared to a physical environment. Both environments ran individual and simultaneous application simulations to not only show real world performance possibilities and results, but also the resource and performance management capabilities of XenServer 6.0. The test beds used by ESG Lab are shown in Figure 3 and Figure 4. Figure 3 shows the Intel server running Window Server 2008 R2 with 64 cores used for physical server testing. The server was connected to a dual-controller LSI storage array via a one gigabit iscsi connection. Figure 3. ESG Lab Test Bed Physical Server Only Figure 4 shows the same physical machine, but now it is running XenServer, allocating eight cores and 24 GB of memory to four separate virtual machines running Windows 2008 R2 Enterprise Edition. Each virtual machine was connected to the LSI storage array via a 1 GbE iscsi connection. Each VM was allocated storage space on the LSI array and assigned drive letters accordingly. Figure 4. ESG Lab Test Bed Virtual Machines on Physical Server

Lab Validation: Citrix XenServer 6.0 6 Conversion Citrix has a physical-to-virtual conversion tool, named XenConvert, which assists in the shift to a virtual environment. XenConvert takes Windows operating systems, applications, or data from a physical server and converts them to virtual machines within XenServer as virtual appliances or virtual disks. ESG Lab Testing After completing the testing required with the physical test bed, ESG Lab moved to the virtual test bed. ESG Lab used XenConvert to convert the physical test bad to a virtual test bed. ESG Lab noted that XenConvert s easy-tofollow wizard-driven interface provided guidance during the conversion. Figure 5 shows a XenConvert interface. This interface was used to provide storage space allocation details for a particular virtual environment. Figure 5. XenConvert 2.4 Utility Storage Space Allocation Four VMs, all running Windows Server 2008 R2, were created on the XenServer. ESG Lab maintained the integrity of all applications and external storage during the XenConvert process. The change to the virtual solution was smooth and quite impressive. Why This Matters Under-utilized servers that take up space and are improperly aligned with their supported workloads can quickly lead to resource limitations. This unnecessary resource consumption continues to be a challenge faced by many IT professionals. A successful virtualization implementation is a direct result of properly consolidating and migrating physical and virtual machines. Creating a cost-effective infrastructure can not only save money, but also time. ESG Lab confirmed that the migration from a physical environment to a virtual environment with Citrix s wizarddriven interface continues to be both quick and easy. 2 2 See: ESG Lab Report, Citrix XenServer: Complete, Cost-effective Data Center and Server Virtualization, September 2010.

Throughput (IO/s) Performance Lab Validation: Citrix XenServer 6.0 7 Application performance can change when moving from a physical to a virtualized environment due to a potential for different resource utilization. It is very important for an IT organization to verify similar application performance in both environments to insure the move to a virtual environment is acceptable. ESG Lab used three industry standard tools to simulate four different workloads. The application simulations were run both individually and simultaneously in each test bed. The goal was to find the total throughput impact when switching from physical to virtual servers, as well as response time changes due to new performance overhead introduced by the Xen hypervisor. Microsoft Exchange Server Jetstress 2010 is a Microsoft tool used to simulate disk IO on an exchange server. Jetstress 2010 works with the Microsoft Exchange Server 2010 database engine to simulate Exchange database and log disk input/output load. Jetstress simulates the Exchange database and log file loads produced by a specified number of users. 3 SQLIO is a Microsoft tool used to determine the IO capacity of a given configuration. ESG Lab used an 8KB random IO workload with this tool. 4 Iometer is an open source workload generation tool. ESG Lab used Iometer to generate two simulated applications: a backup reader and a web server. The backup reader workload mimics the behavior of a backup application during a restore operation with a default block size of 64 KB. The web server workload is meant to mimic the IO activity of a web server, such as Apache. 5 ESG Lab Testing In the physical testing scenario, all four workloads ran on a single physical server to different parts of an LSI 2600 storage array. The virtual testing scenario differed in that each of the four virtual machines was designated one workload each. The storage remained the same between the physical and virtual test cases. Figure 6 shows the results of running four applications simultaneously in both environments. Figure 6. Physical vs. Virtual Total IO/s 1,400 Total Throughput Applications running simultaneously 1,200 1,000 800 600 400 SQLIO Backup Reader Web Server Jetstress 200 0 Physical Virtual 3 http://www.microsoft.com/download/en/details.aspx?id=4167 4 http://www.microsoft.com/download/en/details.aspx?id=20163 5 http://www.enterprisestrategygroup.com/using-esg-lab-workloads/

Lab Validation: Citrix XenServer 6.0 8 Figure 7 shows the throughput of running the backup reader simulation as an individual application in both environments. Figure 7. Backup Reader Throughput Backup Reader Throughput Individual application workload Virtual Physical 1 3 5 7 9 11 13 Throughput (MB/s) What the Numbers Mean As seen in Figure 6, the total throughput for all workloads running simultaneously is 8% lower on virtual machines than on a physical machine. Individual application throughput while running with other applications varies between the two test cases due to different resource utilization. This can be seen when comparing throughput of the backup reader and web server. Figure 7 shows the results of running backup reader as a single application. The physical test bed yielded 15% more MB/s than the virtual test bed. Why This Matters The Xen hypervisor is a software layer that runs directly on server hardware. This gives the hardware the ability to run multiple Windows and Linux operating systems in parallel. Consequently, these concurrent operating systems cause performance overhead for applications that utilize the same hardware at the same time. The overheard impacts the types of applications that can run in a virtualized environment, as well as how many applications can be virtualized from a given physical server. ESG Lab measured performance overhead to be 8% when running a collection of applications in a virtualized environment as compared to running the same applications together in a physical environment this is more than acceptable. The minor impact to performance is more than justified by XenServer s ability to help save money by better utilizing physical resources.

Response Time (ms) Lab Validation: Citrix XenServer 6.0 9 ESG Lab ran an 8K random, read workload using SQLIO. Figure 8 shows the latency differences between the virtual and physical environments. Figure 8. SQLIO Latency SQLIO Latency Lower average latency is better Virtual Physical 1 3 5 7 9 11 13 Average Latency (ms) Jetstress was configured to emulate 1,200 users with 200 MB mailboxes performing typical Exchange operations at an IO rate of 0.12 IOPS per mailbox. A response time goal of 20 milliseconds or less for database reads is required to pass the test. These values are defined by Microsoft as a limit beyond which end-users will feel that their e-mail system is acting slowly. 6 Figure 9 shows the latency differences from running Jetstress as an individual application in both environments. Figure 9. Jetstress Latency 25 Jetstress Average Read Latency (Less than 20ms to pass) 20 15 10 Required Physical Virtual 5 0 6 http://technet.microsoft.com/en-us/library/bb738152(exchg.80).aspx

Lab Validation: Citrix XenServer 6.0 10 What the Numbers Mean Faster response times are seen on the physical test bed, as opposed to 10% degradation in the virtual environment. This can be seen in Figure 8. Figure 9 shows the average read latency of the Jetstress testing. Response times increased slightly, but not to the extent that users would notice. Physical and virtual response times were within the 20ms Microsoft guideline. ESG Lab installed Microsoft SQL server on a physical server and virtual server and timed two different SQL scripts. Before running the scripts, a table was created within a duplicated production database from ESG s internal IT operation and a large number of rows were added to the new table. The first script was a basic SQL query selecting everything from the newly-created table. The second script contained an SQL query consisting of a three table join. Each script was timed and the average duration of each script was recorded. Table 1 shows the results from the basic SQL query and the more complex SQL query. Table 1. SQL Server Results Operation Time in Seconds Physical Virtual Difference Basic Table Select 5.92 6.29 6% Three Table Join 287.00 315.60 10% Why This Matters Performance scalability is difficult to predict, especially with multiple, complex applications sharing a physical server s resources. A sudden change in application performance due to a burst of processing power or IO activity can negatively impact application response times. Slower response times can result in the loss of productivity, loss of competitiveness, loss of customer goodwill, and, potentially, loss of revenue. Top tier applications, such as Microsoft Exchange and Microsoft SQL Server, can cause these negative impacts if not properly deployed. Finding a perfect balance of performance, availability, and cost effectiveness is critical for IT executives. ESG Lab confirmed that the low response time difference while independently running Jetstress and SQL Server on a virtual machine when compared to a physical machine is more than acceptable. The minimal response time impact in the virtualized environment will be undetectable to both end-users and applications alike. Also, the Microsoft guideline for average latency was comfortably reached when running the Microsoft Exchange simulation in a virtualized environment.

Lab Validation: Citrix XenServer 6.0 11 Manageability and Optimization Citrix XenServer is managed by the XenCenter graphical user interface. Dynamic memory control and performance monitoring tools give XenCenter the flexibility to effectively manage a XenServer deployment. These features allow IT professionals to recognize where and when resource limitations are occurring, and arm them with the ability to adjust resource usage for continued, acceptable performance in a virtualized environment. Dynamic Memory Control Dynamic Memory Control (DMC) is a tool available in XenServer Advanced Edition and can be managed through XenCenter. Whether powering on more virtual machines within a physical server or consolidating virtual machines during business downtime, DMC gives IT professionals much-needed flexibility to manage their XenServer resource pool environments. As seen in Figure 10, ESG Lab configured three virtual machines with static memory settings. The first two VMs were powered on with their static memory settings fully utilizing all of the memory allocated to the resource pool. The third VM was powered off. Figure 10. XenCenter Memory View Figure 11 shows the results of attempting to power on the third virtual machine. Due to the fully utilized resource pool memory and the first two VMs having static memory settings, ESG Lab was unable to power on the third VM. Figure 11. VM Starting Error Prompt

Lab Validation: Citrix XenServer 6.0 12 ESG Lab then configured the first two VMs with dynamic memory settings by setting a minimum and maximum memory requirement as shown in Figure 12. Figure 12. Edit Dynamic Memory Settings Finally, Figure 13 shows the results when ESG Lab powered on the third VM after adjusting the memory settings of the first two VMs to utilize DMC. The used memory of the first two VMs was automatically adjusted to allow the third VM to power on. Figure 13. XenCenter Memory View with Dynamic Memory

Performance Monitoring Lab Validation: Citrix XenServer 6.0 13 XenCenter gives administrators the ability to monitor, in both real-time and historically, the way system resources are being utilized in the virtual infrastructure. Performance data about each XenServer and each virtual machine within a XenServer is automatically collected. These results can be seen at various levels of granularity, from seconds and minutes up to one year, within XenCenter. Figure 14 shows an example of what to expect when viewing the performance tab for a particular VM. Three graphs were displayed, showing statistics about CPU utilization, network traffic, and memory usage. Figure 14. XenCenter Performance Monitoring View Adding new performance graphs was quite intuitive. ESG Lab selected the configure graphs button to present a list of possible statistical counters. After selecting the desired counters, a graph was then added to the overview screen and real-time monitoring began. Why This Matters Flexibility in IT is becoming a necessity. System resources can quickly become over-utilized with unpredictable workloads from various business applications. Responding quickly to an application s performance demands is no longer a wish it is an expectation. Application interruptions are unacceptable in many business environments. ESG Lab verified XenServer s ability to optimize resource utilization and monitor performance in real time. DMC was able to fluidly adjust system memory resources without interrupting the other VMs. The performance graph overview was able to accurately show the percentage of resources needed to run multiple applications throughout the entire virtualized environment.

Lab Validation: Citrix XenServer 6.0 14 ESG Lab Validation Highlights The migration from a physical server to a XenServer was quick and easy. ESG Lab was able to quickly create multiple VMs on the XenServer through XenCenter with minimal effort. The virtual environment running the simultaneous application simulations yielded 8% lower IO/s than the physical environment. ESG Lab believes this to be more than acceptable with all of the other advantages XenServer offers. Dynamic Memory Control was validated by ESG Lab by attempting to power on a static-memory-allocated virtual machine with two other virtual machines utilizing all of the allocated memory. The memory usage was able to dynamically adjust to allow the third virtual machine to power on. ESG Lab was able to use XenCenter s performance monitoring tool to view current resource utilization including CPU, network traffic, and memory usage during application simulations. This included the ability to add new counters and graphs while monitoring the existing counters in real time. Issues to Consider Testing of Citrix XenServer exposed ESG Lab to the XenCenter management console. The console provided a single pane of glass, multi-server management interface for the XenServer environment. It is, however, a Windows application only and must be deployed on the Windows platform; this must be taken into consideration when planning deployment of a XenServer environment. ESG Lab used the XenConvert tool to migrate from a physical environment to a virtual environment. This tool, like XenCenter, is limited by its operating system dependency: Windows. That being said, XenConvert can create virtual Linux environments from a physical Windows environment. With features like XenConvert and Dynamic Memory Control, ESG Lab found that Xen server provided real flexibility and agility for migrating and consolidating physical servers and applications into a virtual environment. However, it does not eliminate the need for proper planning and best practice implementation. A properly sized and architected virtual infrastructure, along with a clear understanding of minimum resource requirements, is critical to avoiding stability and performance issues while meeting customer SLAs.

The Bigger Truth Lab Validation: Citrix XenServer 6.0 15 Application performance in a virtualized infrastructure continues to be a challenge faced by IT professionals. Performance bottlenecks remain a concern, specifically with IO-intensive, enterprise applications. With the increased use of virtualization continuing to be a top IT priority, 7 the movement of high-throughput-demanding applications to a virtual solution will become a necessity rather than an option. Coupled with a continued need for better resource utilization while continuing to cut costs, a major dilemma quickly presents itself. Where should the sacrifice come from? Performance? Cost? Reliability? The reduction of operational costs while continuing to meet demanding business requirements is a mandate for many businesses. Consolidating server workloads, dynamically optimizing workloads, and disruption-free reliability are key criteria when selecting a more flexible virtual platform to help leverage your existing infrastructure. Maintaining acceptable application performance while satisfying the aforementioned criteria creates a recipe for an ideal IT infrastructure. Through hands-on evaluation and testing, ESG Lab has confirmed that Citrix s XenServer has all of the capabilities necessary to address each of these challenges in a simple, affordable way. Tools, such as XenConvert, make the convergence to a virtual environment a breeze, with immediate accessibility to your virtual machines upon completion. The manageability provided by XenCenter creates an easy, navigational view between a virtual infrastructure and administrator. The ability to see resource utilization over time and in real time gives IT professionals the ability to be proactive when bottlenecks begin to present themselves. With dynamic memory allocation, XenCenter can provide a better understanding of how applications consume resources without sacrificing resource integrity. ESG Lab has verified that acceptable performance scalability was attained using XenServer, both at a throughput and a response time level. Minimal degradations are expected when moving from a physical environment to a virtual environment, and those seen during ESG Lab s evaluation are well within expectations. ESG Lab has confirmed that Citrix XenServer is a powerful, cost-effective, integrated server virtualization solution. 7 Source: ESG Research Report, 2011 IT Spending Intentions Survey, January 2011.

Appendix Lab Validation: Citrix XenServer 6.0 16 Table 2. ESG Lab Test Bed Server 2U form factor chassis Intel Development Server 64 CPU cores 128 GB RAM Storage Dual controller LSI 2600 Storage Array 1 Gigabit iscsi connectivity 96 SAS 15K disk drives Network 1U rack mount network switch Dell Network Switch PowerConnect 1/10 GbE Model 8024 Software Citrix XenServer Version 6.0 Windows virtual machines Windows 2008 R2 Iometer 2008.06.18 Jetstress Exchange Server 2010 Microsoft SQL MSSQL 2008 R2

20 Asylum Street Milford, MA 01757 Tel:508.482.0188 Fax: 508.482.0218 www.enterprisestrategygroup.com