Cost Efficient VDI XenDesktop 7 on Commodity Hardware (Part I)

Introduction

An increasing number of enterprises are looking towards desktop virtualisation to help them respond to rising IT costs, security concerns, the user demands of BYOD and mobile working strategies. But can a desktop virtualization solution have a lower or equivalent Total Cost of Ownership (TCO) when compared to the traditional approach of procuring physical desktops? Is there a solution which delivers all the benefits of scalability and performance while maintaining a lower TCO?

Leveraging commodity hardware is the answer – by enabling the delivery of a desktop virtualisation infrastructure that modernises the workforce and enhances user productivity while maintaining a lower TCO. The team at Boston Limited have collaborated with Citrix to leverage a Supermicro based commodity hardware stack and design a robust yet scalable XenDesktop architecture.

The solution works using software components such as Citrix XenDesktop 7.1 in combination with Microsoft Hyper-V 2012 R2 and Windows Storage Spaces. The hardware stack includes traditional 19” rack based servers equipped with SATA 6Gb/s 7mm 2.5″ SSD for hosting an IOPS intensive write cache and two 10 core Intel® Xeon® E5-2680 V2 processors for servicing the Hosted Shared Desktop workload; catering for both heavy task based and knowledge workers. The architecture does away with the need for a traditional SAN and relies on a simple SAS JBOD managed by Windows Server 2012 R2 clustered file services for hosting user data.

 

Solution Objective

The objective of this guide is to validate a Citrix XenDesktop Hosted Shared Desktop architecture on commodity hardware whilst keeping a consideration the business needs of organizations. The solution is designed to deliver performance and reliability on par with enterprise class hardware yet keeping the per user capital expenditure for storage, compute and network well within the range of $125 USD for deployments of 1,000 users or greater.

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The Relevance of Commodity Hardware

‘Commodity Hardware’ is hardware that is both easily affordable and available. A device that is said to use “Commodity Hardware” is one that uses industry standard building block components that are available from a variety of different manufacturers; they are already available or designed for a mass market and are thus not necessarily proprietary or unique to that device. Commodity hardware solutions are often employed and used as file servers or are clustered together by enterprises to provide large-scale computing power, or to maximize savings in IT design.

Based on the ongoing research efforts, and the continuing advancements of computing and networking technology, it is believed that use of commodity hardware is vital in creating a cost effective and easily scalable cloud solution. And this is poised to have a major impact on our society’s data centric commercial and scientific endeavours.

Applying this concept, Citrix and Boston Limited have built a cost-effective yet powerful and scalable virtual desktop infrastructure at a price point lower or equivalent to that of a traditional PC.

 

XenDesktop 7 on Commodity Hardware

Each of the desktop class servers is equipped with 20 x 2.8 GHz Intel Xeon Ivy Bridge processor cores and 256GB RAM to satisfy the compute needs of shared desktop workloads for up-to 200 users. A key differentiator is the use of enterprise class SATA Solid State Drives which provide excellent endurance from low-cost 19nm NAND. The cost of these drives is 1/3 that of SLC NAND based SAS SSDs. Each server is equipped with 2 x SanDisk CloudSpeed 1000 series SSDs. Two of these drives configured with Windows Server 2012 R2 Storage Spaces are utilized to host the volatile Write Cache and can service write IOPS in the range of 100 per user thus effectively managing boot / login storms and IO intensive operations such as antivirus scanning.

The construct of this Citrix Validated Solution is based on many decisions that were made during validation testing. Testing was carried out using the Login VSI 4.0 Virtual Session Indexer (VSI), an industry standard tool for user / session benchmarking. Login VSI allows comparisons of platforms and technologies under the same repeatable load. The “Medium” VSI workload is expected to approximate the average office worker during normal activities and was the workload used throughout testing.

The testing was conducted on a scaled down replica of the expected production environment. Only the Hosted Shared Desktop FlexCast model workloads were tested using the XenDesktop Template Policy “High Server Scalability” running in “Legacy Graphics mode”. Therefore the Bill of Materials described within this document is extrapolated based on single server scalability test results with these policy settings in place. Using these Citrix Policies allows the greatest host density for each FlexCast model.

The following figure depicts the solution architecture that make up the requirements for delivering a XenDesktop 7 Hosted Shared Desktop solution onto commodity hardware.

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The following Citrix and Microsoft components are required to deploy the reference architecture:

  • Citrix XenDesktop 7.1: Hosted Shared Desktop and App virtualization platform
  • Citrix Provisioning Server 7.1: Workload delivery platform
  • Citrix StoreFront Services 2.1: Desktop and app resource enumeration
  • Microsoft SQL 2012 SP1: Database Platform
  • Microsoft Hyper-V Windows Server 2012 R2: Hypervisor platform
  • Microsoft Windows Storage Server 2012 R2: Storage management platform
  • Hardware: Boston Servers, Switches and Storage