Increasing performance and lowering the cost of storage for VDI With Virsto, Citrix, and Microsoft

Increasing performance and lowering the cost of storage for VDI With Virsto, Citrix, and Microsoft 2010 Virsto www.virsto.com

Virsto: Improving VDI with Citrix and Microsoft Virsto Software, developer of the first and only hypervisor-resident storage solution built from the ground up to optimize storage for virtualization, has teamed with Citrix Systems and Microsoft to demonstrate significant boosts in end user VDI performance. At the same time, adding Virsto Software to a Microsoft-Citrix VDI configuration dramatically reduces the total cost per desktop by slashing storage capital and operating expenses. Recently, Microsoft, Citrix and Virsto performed joint solution tests at the Microsoft Technology Center (MTC) in Mountain View, California. This document provides an overview of the combined Virsto, Citrix, and Microsoft VDI solution, and describes the benefits and cost savings IT organizations can achieve when deploying the combined solution. In this report, the results of the MTC tests are presented and analyzed. The Lure of VDI Organizations are attracted to virtual desktop infrastructure (VDI) because of its significant benefits, including increased user flexibility via desktop access from any device over any network connection, and reduced costs from removing infrastructure from remote desktops. The business benefits of VDI do not stop there, however, and include: Improved compliance with internal and external standards Faster deployment of new operating systems and applications across a variety of hardware types Increased user application reliability and uptime via automated failover and recovery VDI's VM Storage Challenges Because of these benefits, use of VDI is growing rapidly. However, early adopters have found storage to be the Achilles Heel of VDI. VDI uniquely stresses storage, and traditional storage technologies fall short in three key ways: 1. The run-time I/O performance demands of VDI are in general not terribly taxing. However, heavy bursts of I/O are required at key times, such as when many VMs are booted early in the day in preparation for employees arrival or when many users login on a near simultaneous basis. Boot storms, which demand heavy read I/O, and login storms dominated by writes, can force vast over-provisioning of storage hardware to handle such bursty demand. In some VDI environments, application storms demand heavy read and write I/O when multiple clients are simultaneously access a specific application such as Microsoft SharePoint. 2. Then there are the performance issues that impact IT. How long does it take to clone dozens, hundreds, or thousands of virtual desktop images? Does VM image creation require meticulous orchestration of the cloning process or require ultra-expensive storage hardware to meet requirements for speedily standing up VMs? 3. No matter what the primary goal of a VDI project, TCO is critical. Data center storage can cost up to 10X more than the same number of desktop terabytes. Moving storage from desktops Virsto, Citrix, and Microsoft VDI Solution 1 2010 Virsto

into the datacenter can therefore make the TCO of VDI economically infeasible. When storage costs swamp other savings, the viability of a VDI project comes into question. Virsto Benefits for a Citrix and Microsoft VDI Deployment Virsto significantly reduces the cost and complexity of VDI deployment and improves users' perceived desktop performance with a software-only solution that supports any block storage hardware. Virsto s software, Virsto One, is a simple solution installed in the parent partition of Microsoft Hyper-V. Unlike storage technologies designed prior to the emergence of x86 virtualization, Virsto s patent-pending architecture deals with the unique performance demands of VDI without requiring special hardware or appliances. Recent benchmarks performed jointly with Virsto partners Microsoft and Citrix demonstrated that Virsto One can cut the time to boot XenDesktop images by up to 3x and can reduce total login times by up to 9x. Virsto understands that VDI has an enormous appetite for space-efficient VM image clones created from golden images. Virsto One is therefore built to rapidly deliver a virtually unlimited number of high performance clones. Because Virsto One disk image clones share common data blocks among many images, total requirements for terabytes of physical disk space are greatly reduced. In a recent benchmark, 95% less VDI storage capacity was required. Additionally, the unique architecture of Virsto One dramatically reduces the need for expensive caches, solid-state disks (SSDs), or arraybased software licenses. Because Virsto One runs on any block storage devices, from high-end Fibre Channel systems with flash SSDs to the lowest cost commodity hardware, IT organizations have freedom to choose storage hardware that is cost-optimized for their specific VDI requirements. To summarize, Virsto s software is specifically designed for virtual servers and VDI. With Virsto you can: Improve perceived end user desktop performance at boot, login, and run time Achieve up to triple the I/O throughput with existing hardware Run more VMs per server and per disk spindle Reduce VM image storage footprint by up to 90% or more Reduce VM storage provisioning time from tens of minutes to less than a second per VM Simplify and speed up data backup Cut your VM storage budget by half or more Reduce cost per desktop for VDI implementations Virsto, Citrix, and Microsoft VDI Solution 2 2010 Virsto

The Deployment Scenario In this test, an 84-seat Citrix XenDesktop 4.1 environment was deployed on Dell EqualLogic PS5000 storage hardware using the iscsi protocol. Four Dell PowerEdge M605 blade servers with 8 cores and 32GB RAM each ran the infrastructure components and the VDI VM instances. Figure 1 illustrates the configuration. Figure 1: Configuration overview One host server was used for infrastructure components: Microsoft System Center Virtual Machine Manager (SCVMM) Citrix Desktop Delivery Controller (running on Microsoft Windows Server 2003) Citrix Provisioning Server (running on Microsoft Windows Server 2008 R2) Three remaining host servers ran Microsoft Windows Server 2008 R2 Hyper-V and XenDesktop VM instances: Up to 28 images per host each running Windows 7 with 1GB RAM allocated to each instance The infrastructure components (Provisioning Server, Desktop Delivery Controller, SCVMM) were configured to run as separate virtual machines on a dedicated Hyper-V host. The infrastructure host was running Virsto One and all the virtual machines were configured to run with Virsto One VHDs. XenDesktop was tested in two configurations: 1. Private image mode Each desktop instance is a separate Windows 7 (32 bit) instance bootable from a dedicated VHD image. The logical size of each image is 25GB. 2. Standard mode Boot streaming the same Windows 7 image from a Provisioning Server, each desktop instance had a write cache VHD attached to it. The logical size of each write cache VHD was 10GB. Virsto, Citrix, and Microsoft VDI Solution 3 2010 Virsto

Figure 2 illustrates the internals of the storage and servers for the test. Figure 3 shows the storage configuration. Figure 2: Internal view of server configurations Figure 3: Storage configuration Virsto, Citrix, and Microsoft VDI Solution 4 2010 Virsto

Test Results and Value Proposition for Citrix and Microsoft VDI Implementations The following sections outline the value propositions associated with using Virsto One with Microsoft Hyper-V in a Citrix VDI deployment, and summarize the benefits seen in the test configuration. 1) Storage Performance Issue - Boot, Login and Application Storms VDI puts unique strains on storage performance. In VDI, the number of VMs per physical server is typically much larger than in traditional server virtualization. Further, VDI tends to be more write biased, typically 80% (or more) writes versus 20% reads. The particularly write intensive, random I/O generated by VDI has can severely harm perceived end user desktop performance. Technically, the problem is known as the VM I/O Blender, and the result is that total I/O throughput of a physical server drops precipitously as VMs are added. Without Virsto One, the only known way to solve the problem is by vastly over provisioning storage hardware, which significantly adds to the cost of a VDI environment. I/O performance issues are especially noticeable at boot up of each VDI instance and simultaneous login by many end users when they come into the office in the morning. The boot storm issue can be only partially mitigated by spacing out the boot time for the VDI instances prior to employees arrival, a method that adds administrative complexity. The pain of the VM I/O Blender is more dramatic at login, as this cannot be staged. The same can be said about the application storm when thousands of clients are interacting with centralized enterprise applications such as SharePoint. The type of Citrix VDI disk images, when served by Microsoft Hyper-V, is an important design consideration. Stock Hyper-V provides a few options for virtual hard disks, known as VHDs. Dynamic VHDs have the benefit of some space efficiency, because they are thinly provisioned. However, dynamic VHD write performance is not ideal, and experts recommend not using them in most production environments. 1 Fixed VHDs are not thinly provisioned, but have superior I/O performance characteristics. Unfortunately, they occupy far more disk space, which drives up the cost of a VDI implementation. In addition to the fixed/dynamic decision, implementers must decide whether each VHD should be its own full copy of the VM. In a VDI environment, almost all of the data inside the VM (the operating system, etc.) is the same across all instances. In large implementations, this can result in enormous wastage of disk space. Snapshot and cloning technologies available from Microsoft and others can be used to share common data blocks across many VHD images; however, these features often have unusable I/O performance, so are often not recommended for VDI. 1 When working with virtual hard disks, remember to always avoid dynamic VHD files as dynamic VHDs will degrade performance considerably. XenDesktop Design Guide For Microsoft Windows 2008 R2 Hyper-V http://support.citrix.com/article/ctx124687 pages 10-11 Virsto, Citrix, and Microsoft VDI Solution 5 2010 Virsto

With Virsto One, compromises need not be made between disk space savings and VDI end user performance. Virsto One also does not impose many of the limitations inherent in Microsoft s native CSV implementation. 2 Virsto VHDs are always thinly provisioned; yet provide better I/O performance than thickly provisioned alternatives. Further, Virsto s unique ability to provide an unlimited number of high performance clones from a small number of golden images generally results in a 90% or more reduction in the amount of raw disk space required for XenDesktop VDI. By including Virsto One in a Citrix-Microsoft VDI solution, boot time, login time, and application access time can be dramatically improved without the need for additional storage or special storage hardware. In the test scenarios described here, Virsto increased performance as follows: Boot storm performance improvement: up to 3x versus dynamic VHDs Logon storm performance improvement: up to 9x versus dynamic VHDs Run time I/O performance improvement: up to 10x compared to dynamic VHDs, 4X versus fixed Figure 4 compares the time required to boot XenDesktop instances using fixed VHDs (somewhat fast, but requiring much more disk space), dynamic VHDs (less disk space required, but much slower performance), and Virsto VHDs (which take significantly less disk space than dynamic VHDs and deliver much higher performance than fixed VHDs the best of all possible worlds). Figure 4: Boot time comparison across VHD types 2 Ibid. pages 4-5 Virsto, Citrix, and Microsoft VDI Solution 6 2010 Virsto

For the same VDI implementation, Figure 5 illustrates the throughput performance gains seen when deploying Virsto into a Citrix/Microsoft VDI solution. The performance in I/O operations per second (IOPS) with Virsto are 3-4x, without the need to add additional storage hardware. Note that Figure 5 compares thinly provisioned Virsto VHDs against thickly provisioned fixed VHDs; the performance advantage of Virsto compared with dynamic VHDs is much greater. Figure 5: Overall VDI storage performance benefits using Virsto 2) Provisioning Performance Increase When deploying a Citrix and Microsoft VDI solution, write back cache must be provisioned for each XenDesktop instance. This is easy if only a small number of VDI instances are deployed. However, most customers are deploying hundreds to thousands of desktops. Each XenDesktop instance has a fixed VHD that requires a write back cache that is typically around 10GB. When a VDI instance is created, this 10GB write back cache must be copied. So if you have 1,000s of VDI instances you will need to copy a 10GB write back cache for each instance, which would be an extremely long process of creating many instances of that 10GB cache VHD. For instance, 1,000 VDI instances x 10GB write back cache = 10TB Creating large numbers of 10GB fixed VHDs can take many hours. 3 Virsto can dramatically reduce the provisioning time of new VDI instances from hours to just a few minutes. For example, in the joint 3 Ibid. pages 15-16 Virsto, Citrix, and Microsoft VDI Solution 7 2010 Virsto

testing Virsto did with Citrix and Microsoft, creating 56 VDI instances without Virsto took up to 2 hours. With Virsto this same process was 100x faster. 3) Dramatic Savings in Storage - Realizing True Benefit of Virtualization Virtual desktop infrastructure is supposed to reduce the cost of desktops in both capital and operating expenses. However, storage spending can dominate the TCO, to the extent of ruining the economic viability of VDI. Deploying VDI often necessitates significant upgrades to storage infrastructure to meet performance requirements, and the cost of new, over-provisioned storage with special caches and SSDs to deliver adequate burst performance can be enormous. For example, to achieve adequate end user performance, a XenDesktop customer recently discovered that the incremental cost of adding flash-based storage hardware to already-expensive storage arrays added US$1 million in unplanned hardware capital cost. VDI adoption would accelerate at a faster pace if the ROI could show significant savings not only on the desktop side but also within the data center around storage for both performance and capacity. Virsto Software provides this ability to customers deploying a Virsto-Citrix-Microsoft VDI solution. Figure 6 shows the amount of physical disk space required to deliver the performance shown in Figure 4. The amount of space required using Virsto One is so small it barely shows on the graph when compared to dynamic or fixed VHDs. Less storage, higher desktop performance, lower administration cost, and no storage hardware upgrade: it all adds up to a reduction in the cost of VDI deployment using a Citrix-Microsoft-Virsto solution. Figure 6: Space consumption savings with Virsto Virsto, Citrix, and Microsoft VDI Solution 8 2010 Virsto

Conclusions The impact of storage on a VDI project s total cost per desktop and end user experience is undeniable. By not implementing hypervisor based storage services to address the storage inefficiencies, VDI users and vendors will continue to struggle with the following implications of doing the same thing: 1. Overprovision storage hardware. Buy more storage, buy higher end storage arrays, and spend extra money on specialized cache, SSDs, and software features. This means a dramatically higher cost per desktop. 2. Use difficult-to-deploy methods such as fixed VHDs that add to the time and expense of desktop provisioning. 3. Defer implementation of VDI. Virsto One is a better way. Adding Virsto software to existing hardware in a Citrix-Microsoft VDI environment can significantly: Dramatically reduce cost per desktop for VDI implementations Improve end user desktop performance at boot, login, and run time Cut your VM storage budget by half or more Achieve up to triple the I/O throughput with existing hardware Run more VMs per server and per disk spindle Reduce VM image storage footprint by up to 90% or more Reduce VM storage provisioning time from tens of minutes to less than a second per VM Simplify and speed up data backup Contact Virsto Software to learn how. Virsto, Citrix, and Microsoft VDI Solution 9 2010 Virsto