xenserver 5.5 single server scalability with xendesktop 4.0_v2_1004

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Citrix XenDesktop 4 Single Server Scalability Test Results on Citrix XenServer 5.5

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Contents

Executive Summary ................................................................................................................... 3 Test Environment ...................................................................................................................... 4 Test methodology ..................................................................................................................... 5 Data Analysis ........................................................................................................................... 6 Summary of Results ................................................................................................................... 7 Appendices ............................................................................................................................. 9

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Executive Summary

Objectives of the Testing

The purpose of this test was to provide the data needed to substantiate the maximum number of Windows XP virtual desktops per host for XenServer 5.5 using XenDesktop 4). This information provides a data point that customers may reference in designing their own implementations. It is not intended to provide a comprehensive set of tests, workloads, hardware evaluations, etc., and many factors can influence whether other tests will experience the same results.

Methodology

Testing was done in Citrix test labs and utilizing servers with Intel Nehalem processors. The Nehalem utilizes Hyperthreading technology, providing an ideal environment for producing high VM densities per CPU core. Our test results with these servers suggest the possibility that they may well be the “sweet spot” for VDI. Additionally, we chose to use a load test program provided by Login Consultants, known for their expertise in testing VDI and terminal services.

Findings

Under these test conditions, XenDesktop 4 with XenServer 5.5 is able to host 130 Windows XP virtual desktops, each one performing a complex series of real-world user simulations, on a dual socket Intel Xeon x5570 (Nehalem) server with 72GB RAM. The testing was all conducted on the currently shipping version of XenServer software, and no non-publicly available software improvements were used to demonstrate this scale. Although efforts were made to simulate real desktop user workloads, results can and will vary based on a wide variety of factors, including the OS and especially the demands of the workload used, as well as choice of server hardware. These tests results are an example of what is possible under specific conditions, and do not present the full characterization of XenDesktop scalability with XenServer.

Dual socket, quad core, 2.93GHz, 72GB

XenServer 5.5 133 XP Desktops Started

VMs per host 130

VMs per CPU core 16.25

Results are detailed in the appendices section of this document.

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Test Environment

8GB vDisk

1.5GB

1.5GB1.5GB

Net App

3050

Citrix Provisioning Server

Citrix XenServer

5.5

Citrix Desktop 4.0 Delivery Controller

XP Pooled Desktop

XP Pooled Desktop

XP Pooled Desktop

XP Pooled Desktop

XP Pooled Desktop

NFS

Virtual Desktop (1vCPU 512MB)Windows XP SP3Login VSI 2.0: Outlook 2007 Word 2007 Excel 2007 PowerPoint 2007 Internet Explorer 8 Bullzip PDF Printer & Acrobat Reader

PvS Write Cache Disks



ICA Clients

ICA Clients

ICA Clients

ICA Clients

ICA Clients

ICA Clients

Windows 2003 ServersWindows 2003 ServersWindows 2003 Servers

ICA

VHD

Windows 2003 Roaming Profile Server

Windows 2008 ServerSQL Server 2005

for PVS and STAT databases

Figure 1: Citrix XenDesktop 4 Test Environment

Desktop Delivery Controller 4.0

XenServer 5.5

Provisioning Server 5.1.1.2950

Host Server:

o Dual socket Dell PowerEdge R710, x5570, 2.93GHz/72GB RAM

Network: Four GigE NICs used:

o 2 NIC bond used for all guests

o 2 NIC bond used for management and storage.

Clients: Windows XP, 1 vCPU/512MB each

o Storage: Shared, NetApp FAS 3050, NFS

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Test methodology

Tests were conducted a total of three times. Results were collected and averaged. Since all factors were considered to be nearly identical with no external factors involved, results were expected to be relatively consistent from one test to the next. In the event that a given test result was more than 20% off from the other two results, it was deemed that the environment was compromised and repeated.

Workload Simulation

The tests used simulated desktop workloads generated by Login VSI 2.0, from Login Consultants, Netherlands. Using a Citrix tool to automate desktop launches every 15 seconds, the desktop then ran a “medium heavy” workload that ran for 12 minutes and repeated. Like real users, the scripted session will leave multiple applications open at the same time. Every session will average about 20% minimal user activity, similar to real world usage. Note that during each loop, users open and close files a couple of times per minute, which is probably more intensive that most users. During each loop the response time is measured every 2 minutes.

Each loop consisted of:

Outlook 2007, browse 10 messages & type new message.

Internet Explorer, one instance is left open, one instance is browsed to Microsoft, VMware and Citrix (locally cached copies of these websites).

Word 2007, one instance to measure response time (9 times), one instance to review, edit and print a random document.

Solidata PDF writer & Acrobat Reader, the word document is printed to PDF and reviewed.

Excel 2007, a very large randomized sheet is opened and edited.

PowerPoint 2007, a random presentation is reviewed and edited.

3 Breaks (40, 20 & 40 seconds) are included to emulate real world usage

The version of Login VSI used in these tests is freeware and can be downloaded from www.loginconsultants.com.

http://www.loginconsultants.com/

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Data Analysis

Login VSI: Corrected Optimal Performance Index (COPI)

The Corrected Optimal Performance Index (COPI) is a calculated from specific measurements during test runs to determine how many desktops can be run simultaneously without excessively impacting user experience.

The corrected optimal performance index is based on these measurements:

The Uncorrected Optimal Performance Index (UOPI) is based on the first 5 consecutive sessions that hit the ”Optimal Performance Max Reached” threshold The “Optimal Performance Max Reached” value is calculated on the response time average of four sessions higher than 2000ms (4 session average response time > 8000 ms).

The Stuck Session Count (SSC) represents sessions which have become stuck before UOPI, and must therefore be accounted for in the Optimal Performance Index.

The Lost Session Count (LSC) is a count of completely missing log files; these tests are discarded completely in the corrected index.

The Corrected Optimal Performance Index (COPI) is then calculated:

Incorporating the SSC and LSC into a corrected index ensures that the test results are fair and comparable. Therefore, the COPI is calculated as:

COPI=UOPI - (SSC*50%) – LSC

In each case, we ran three individual tests. We then threw out the lowest test score and averaged the remaining top two when recording the overall COPI results. This was done to account for the fact that initial test runs produced lower scores as a result of profiles being established – this was a one-time impact and not representative of ongoing results.

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Summary of Results

To achieve the test result of 130 Windows XP VMs per host server, some key adjustments were made to the XenServer configuration.

Increased the amount of RAM assigned to Dom0 to 2.94GB. The default is 752MB; increasing it

enabled us to launch more desktop clients.

Increased the “Xen-heap” setting to take into account the large number of VMs on this single

server host. This was done by adding "xenheap_megabytes=24" to the Xen command-line in

/boot/extlinux.conf which resulted in an increase from the default of 16MB to 24MB.

Note: Additional information about how to perform these adjustments can be found in the KB article CTX124259.

These adjustments enabled the test to accommodate 133 VMs per host in total. The following is an example of the COPI index report for the one of the test runs:

Total Sessions Launched 133

Uncorrected Optimal Performance Index (UOPI) 133

Stuck Session Count before UOPI (SSC) 2

Lost Session Count before UOPI (LSC) 1

Corrected Optimal Performance Index (COPI = UOPI - (SSC*50%) - LSC)

131

Another way of looking at VM density per host is in terms of the density per CPU, one of if not the most expensive part of the host server itself. Testing with Intel servers using Hyperthreading technology has proven to yield the highest CPU density numbers to date.

Host Server RAM

Host Server CPU cores

# Desktops Launched

COPI Result VM Density

Per CPU Core

72 GB 8 (2x4) 133/Windows XP 130 16.25

While this test demonstrates the ability to support 130 VMs per host, the following considerations should be taken into account:

1. Testing was limited to Windows XP clients. Results for other client OS’ such as Windows 7 may be different due to the requirement of 1GB per client VM.

2. Testing required modification to Dom0 RAM and Xen-heap sizing to optimize performance. Maintaining these at their default settings will likely result in lower density levels.

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3. VM density results are highly dependent upon workload characteristics. We used a workload called Login VSI, created by an independent company, Login Consultants. Login VSI, is well known in the VDI and terminal services community with testing of various terminal services and VDI solutions from multiple vendors in a comprehensive, ongoing test project called Project Virtual Reality Check http://www.virtualrealitycheck.net/. We used the 0default settings in Login VSI 2.0, which called for a medium workload. Customers who may have requirements to test workloads that are either heavier or lighter than those used here, or who may have host servers, storage and other components in their environment which are different from those used here are encouraged to repeat these tests to determine what their VM density per host may be as compared to these results. More information about Login VSI 2.0 can be obtained at: www.loginconsultants.nl.

4. The launch interval used to launch all VMs in these tests was 15 seconds. Changes to launch intervals will likely have an effect on results. Longer intervals will generally improve results while shorter intervals will lead to diminished results.

5. These tests are for XenServer 5.5 and should be revisited as newer releases become available. While Citrix conducted comparative tests with competitor’s products, and determined a very favorable result for XenDesktop on XenServer, Citrix is not at liberty to publish these results due to competitor’s license agreements.

6. All decisions, including which host server platforms to run their virtual desktops on will affect the actual number of VMs per host that any given customer will realize. These tests are simply an example of what is possible under one specific condition

http://www.virtualrealitycheck.net/

http://nieuwsbrief.loginconsultants.com/mailcamp/link.php?M=42074&N=23&L=14&F=H

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Appendices

Test data

Dell PowerEdge r710, Dual Quad Core Intel x5570 72GB RAM

TEST ID: 104 – XenServer – 133 XP desktop Users@15 secs – R710 – #1



Stuck Session count before UOPI (LSC) 2



131

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TEST ID: 105 – XenServer – 133 XP desktop Users@15 secs – R710 – #2



Stuck Session Count before UOPI (SSC) 3



130.5

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Hardware/software information

Citrix XenServer Host Various

OS: Citrix XenServer 5.5 Service Pack:

xxx

Make: Dell Model: See various configuration descriptions

CPU: See various configuration descriptions RAM: 72-256GB

Disk: See various configuration descriptions Network: 4 x 1GbE

XenDesktop Virtual Desktops various

OS: Windows XP 32bit Service Pack:

3

Make: n/a Model: n/a

CPU: 1 x vCPU RAM: 512MB

Disk: 1 x 8GB vDisk, 1 x 1.5GB write cache

Network: 1 x 1GbE

Citrix XenDesktop VDA 4.0.4094

Citrix Provisioning Server Target Device 5.1.1

Login VSI 2.0

Microsoft Office Enterprise 2007 SP2

Internet Explorer 8.0.6001.18702

Adobe Reader 9.1.0

Adobe Flash Player 10.0.22.87

Adobe Shockwave Player 10.2.0.23

Bullzip PDF Printer 6.0.0.865

XenServer tools

Citrix Provisioning Server R900

OS: Windows 2003 64bit Service Pack:

2

Make: Dell Model: R900

CPU: 4 x Intel E7310 1.6GHz RAM: 32GB

Disk: 2 x 73GB 15k SAS Network: 8 x 1GbE (4 in use)

Citrix Provisioning Server 5.1.2950

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SQL Server for PVS R210


1

Make: Dell Model: R210

CPU: 1 x Intel X34xx 2.13GHz RAM: 4GB

Disk: 2 x 50GB 10k SAS Network: 2 x 1GbE

Microsoft SQL Server 2005 64bit Service Pack 2

Databases for PVS/STAT

Citrix XenDesktop DDC 1950B

OS: Widows 2003 R2 64bit Service Pack:

2

Make: Dell Model: PowerEdge 1950

CPU: 1 x Intel Xeon E5310 1.6GHz RAM: 16GB


Citrix XenDesktop DDC 4.0.4094.0

Citrix Web Interface 5.2.0.36

Citrix License Server 1950B

OS: Windows 2003 R2 64bit Service Pack:

2

Make: Dell Model: PowerEdge 1950

CPU: 1 x Intel Xeon E5310 1.6GHz RAM: 16GB


Citrix Licensing 6.8.920

ICA Client Hosts (Specification A)


2

Make: Dell Model: Vostro 220


Disk: 1 x 75GB SATA Network: 1 x 1GbE

Citrix ICA Client 11.1.0.19460

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ICA Client Hosts (Specification B)


2

Make: Dell Model: Vostro 200s


Disk: 1 x 80GB SATA Network: 1 x 1GbE (1 used)

Citrix ICA Client 11.1.0.19460

Infrastructure: XenServer for License Servers Did not use. Used 1950B(DDC) for licensing

OS: Service Pack:

Make: Model:

CPU: RAM:

Disk: Network:

Infrastructure: Active Directory SmokeDC1


2

Make: Dell Model: Vostro 200


Disk: 1 x 60GB SATA Network: 1 x 1GbE

Domain Functional level: Windows 2000 mixed

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Infrastructure: User Profile Server Xen1U


2

Make: Intel Model: Schoffner

CPU: 2 x Intel L5335 2.00GHz RAM: 16GB

Disk: 6 x 60GB SAS Network: 2 x 1GbE

Infrastructure: File Sever ISV3050A

OS: Ontap 7.2.5 Service Pack:

Make: NetApp Model: FAS 3050

CPU: unknown RAM: unknown

Disk: 4x 67GB 15K Network: 4 x 1GbE

Test Tool Infrastructure: STAT Database This is listed above. We used one SQL Server for both PVS and STAT

OS: Service Pack:

Make: Model:

CPU: RAM:

Disk: Network:

xenserver 5.5 single server scalability with xendesktop 4.0_v2_1004

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