virtualization's impact on the desktop - tolly · · 2008-10-1612 vmware esx server...

©2006 The Tolly Group

Document #206138

Virtualization's Impacton the DesktopA Hands-on Assessment of Desktop Virtualization using Citrix, IBM, and VMware Technologies

A white paper commissioned byCitrix Systems, Inc.

WhitePaperAugust 2006

http://www.tolly.com/UTS_Home.aspx

www.tolly.com

WHITE PAPER: Virtualization's Impact on the Desktop


This documentwas authored by:

Kevin Tolly,President/CEOThe Tolly Group

Charles Bruno,Executive Editor

Adolfo Montoya,Senior Engineer

August 2006

2

TERMS OF USAGEEntire contents © 2006 The Tolly Group, Inc. All rights reserved.USE THIS DOCUMENT ONLY IF YOU AGREE TO THE TERMS LISTED HEREIN.

This document is provided, free-of-charge, to help you understand whether a givenproduct, technology or service merits additional investigation for your particular needs.Any decision to purchase must be based on your own assessment of suitability. Thisevaluation was focused on illustrating specific features and/or performance of theproduct(s) and was conducted under controlled, laboratory conditions and certain testsmay have been tailored to reflect performance under ideal conditions; performancemay vary under real-world conditions. Users should run tests based on their own real-world scenarios to validate performance for their own networks. Commerciallyreasonable efforts were made to ensure the accuracy of the data contained herein buterrors can occur.

The test/audit documented herein may also rely on various test tools the accuracy ofwhich is beyond our control. Furthermore, the document relies on certainrepresentations by the sponsor that are beyond our control to verify. Among these isthat the software/hardware tested is production or production track and is, or will be,available in equivalent or better form to commercial customers. The Tolly Group providesa fee-based service to assist users in understanding the applicability of a given testscenario to their specific needs. Contact us for information. When foreign translationsexist, the English document is considered authoritative. To assure accuracy, usedocuments downloaded from The Tolly Group's Web site.

TOLLY GROUP VENDOR SERVICEWith more than 17 years experience validating leading-edge Information Technologyproducts and services; The Tolly Group has built a global reputation for producingaccurate and unbiased evaluations and analysis. We employ time-proven testmethodologies and fair-testing principles to benchmark products and services with thehighest degree of accuracy.

Our "Up-to-Spec" service provides the custom testing complement to the "standard,"granular tests offered in "Tolly Verified". See our Tolly Group Home Page.

Plus, unlike narrowly focused testing labs, The Tolly Group combines its vasttechnology knowledge with focused marketing services to help clients better positionproduct benchmarks for maximum exposure.


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©2006 The Tolly Group August 20063

5 Virtualization Approaches5 Desktop Virtualization6 Ensuring Success with Virtualization6 Virtual Desktop Components7 Performance is a Top Priority7 Test Architecture8 Scalability Test Environment10 Results and Observations10 Citrix Presentation Server Scalability with Remote

Desktop Client12 VMware ESX Server Functionality with

Windows XP Guests13 Focus on Remote Access Performance13 "File Open" Scenario14 DSL Results15 T1 Results15 Satellite Results16 PowerPoint Scenario16 DSL Results

Table of Contents



16 T1 Results16 Satellite Results17 Remote Printing Scenario18 DSL Results18 T1 Results18 Satellite Results

19 Presentation Server Functionality with Virtualized Desktops

20 Citrix Single Sign-on20 Auto-reconnect21 Session Reliability22 Application & User Management23 Smooth Roaming23 Virtual Desktop Success25 Appendix A. Scalability Test Methodology27 Appendix B. Scalability Test Results,

Detailed Charts30 Appendix D. Scalability Testing Tips for a

Virtual Environment using VMware ESX Server

Table of Contents continued



Virtualization's IImpact oon tthe DDesktop

Virtualization ApproachesApplication virtualization is the abstraction of applications from user PCs; thatis, completely removing applications from the end-user device and runningthem on servers in the data center, while maintaining the same localapplication experience, with full use of local devices and printers. CitrixSystems' Presentation Server is an example of technology that can be used tovirtualize applications.

Desktop Virtualization

Citrix Presentation Server offers a compelling solution for desktopvirtualization in the form of published desktops. However, desktopvirtualization can also be the abstraction of operating systems from userPCs by using a virtual machine-based architecture. VMware® ESX andMicrosoft Virtual Server are examples of technology that can be used tovirtualize a hardware environment to host a PC operating system.

The linchpin of any virtualized desktop environment will be remote access.Polished, feature-rich tools are required to effectively manage the flow ofinformation and application sessions between downstream client devicesand back-end servers running the applications and serving the data. Suchremote access solutions have to demonstrate the ability to efficientlyhandle data between chatty, demanding clients, and virtualized machinesrunning on back-end servers that handle the applications processing. Ineffect, these remote access gateways must perform the translationbetween the client world and the protocols supported by the virtualmachine environment. Lastly, the remote access solution must scale tosupport the demands of enterprise networks.

While desktop virtualization is newly emerging, a few vendors havestepped up to the plate to benchmark their combined solution for desktopvirtualization. Citrix Systems, Inc. — along with help from IBM andVMware, Inc. — commissioned The Tolly Group in June 2006 to conduct acomprehensive hands-on evaluation of a desktop virtualizationenvironment combining solutions from Citrix, ESX Server™ software fromVMware, Inc. and IBM System X™ and BladeCenter® servers.

Who benefitsfrom DesktopVirtualization?

Offshore developersRequire full control ofdesktop — reboot,change systemsettings

Mobile workforceRoaming usersrequire remoteaccess to thecorporate desktopimage

Application certificationApplication re-testing on CPS canbe time consuming.Customers/ISVsprefer to certify theirapplications onWindows XP only

Full PC functionality withthin clients

System integratorswill look at virtualmachine clients as areplacement fordesktop PCs for fullWindows XPfunctionality



Ensuring Success with Virtualization

The benefits of moving to a virtual desktop model are plentiful, but makingthe transition to such an infrastructure means that IT architects need toscrutinize the products they intend to deploy to ensure they deliver thecapabilities required for successful operation.

At the top of any desktop virtualization checklist should be scalability andremote access performance. For any desktop virtualization solution to betruly effective on an enterprise scale, it needs to be able to scale tosupport the ranks of enterprise network users.

From a remote access performance standpoint, the key variables areelapsed time to complete key tasks, and the amount of bandwidth used tohandle a transaction. Ideally, the optimal solution will offer a combinationof low elapsed task completion time and low bandwidth consumption.

Virtual Desktop Components

Tolly Group engineers examined a variety of capabilities delivered by the CitrixAccess Suite when used in a desktop virtualization solution. The tested solutionincluded IBM blade servers and VMware virtualization; providing virtualizedWindows XP "desktops" that could be accessed via remote desktopapplications running on the Citrix Presentation Server. In effect, this was a"double-hop" remote access scenario with individual Windows XP remotedesktop sessions passed to the ultimate end users via the Citrix PresentationServer's remote access protocol. (Technically, this was Microsoft's RemoteDesktop Protocol (RDP) to the Citrix Presentation Server and a Citrix ICAstream to the eventual end-user client device.) In this scenario, the Citrixsystem serves as an intermediary or broker, of sorts, between remote endusers and a bank of virtualized desktops in the data center.

Tests focused on scalability, performance, and feature/functionalitycapabilities. Specifically, The Tolly Group focused on determining how maysimultaneous remote control sessions could be supported by the "broker"machine. In addition, The Tolly Group performed functional testing aimed atassessing the solution's suitability for a remote deployment model.

In the pages that follow, The Tolly Group chronicles the scalability of thedesktop virtualization solution, and its ability to meet the expanding needsof enterprise network architects. We examine performance of the solutionin terms of throughput consumed, and elapsed time for common tasks. Andfinally, we examine key functions, such as printing through smooth

6



roaming, single sign-on through Citrix Password Manager, auto-reconnectand session reliability.

Performance is a Top PriorityIn any virtualized desktop environment, performance comes into play atseveral points. Users need to properly size the back-end servers that willhouse the virtual PCs and serve up files and application data as requested.

But an equally strategic scalability point involves the access point thatmanages the PC sessions from downstream clients and back-end servers.

For the purpose of this white paper, The Tolly Group has focused its scalabilityevaluation on the strategic scalability point and the ability of remote clients toaccess a remote gateway that furnishes access to those servers and thevirtualized desktop images.

Test ArchitectureIn the test scenario, IBM, VMware, Citrix and Tolly Group engineers configured andmeasured user scalability on Citrix Presentation Server 4.0 Enterprise Edition (Build2720) 64-bit version and VMware ESX Server 3.0.0 (Build 27701) running on a set ofIBM BladeCenter servers in an IBM lab in Kirkland, WA. (See Figure 1.)

7

Workstations

IBM System X and BladeCenter

Servers

Citrix Access Suite

VMware ESX

VirtualDesktopSolution

IBM System X and BladeCenter

Servers

SOURCE: The Tolly Group, August 2006

FIGURE 1Virtual Desktop Solution Components


Two critical measurements were made as the tests progressed: the number ofWindows XP virtual machine sessions that could be supported on the specificIBM Blade Center configuration under VMware ESX, and the maximum numberof concurrent users creating Citrix ICA sessions between Citrix PresentationServer and VMware ESX Server.

Each user was independent from the other, meaning that each user requesteda unique Windows XP virtual machine out of the ESX Server. The remotesession established between the remote user and the ESX server used theRDP protocol to the Citrix Presentation Server and the Citrix ICA protocol to theend user. This configuration provides benefits to remote users using featuressuch as single-sign on, session reliability, compression and others that theMicrosoft Remote Desktop client and RDP does not offer specifically.

Engineers utilized AutoIt version 3.0 as the primary scripting tool to automatethe test. Citrix, IBM, VMware, and Tolly Group engineers worked in conjunctionto create and simulate two classes of users: "light" users and "heavy" users. Lightusers were categorized as the standard office user that logs into the system andworks on typical business applications such as Microsoft Office. Heavy userswere classified as software developers that usually compiling and executing asample code using Microsoft Visual Studio 2005.

Scalability Test Environment

The test environment consisted of one Citrix Presentation Server 4.0 (64-bitversion) installed and configured on an IBM BladeCenter chassis containingIBM HS20 server blades. The IBM HS 20 blade was outfitted with two single-core Intel® Xeon® processors running at 3.8 GHz, with 8GB of memory, andWindows Server 2003 Enterprise x64 Edition (SP1). This machine served asthe "front end" to the data center machines.

For the "back end" target machines, 17 identically configured HS20 serverblades running VMware ESX were used. VMware ESX 3.0 was installed onthe IBM blade servers, and configured to host 300 virtual machine (VM)instances of Microsoft Windows XP Professional (SP2). (See Figure 2.)

8 August 2006




In order to centrally control all of the VMware ESX servers and the virtualmachines, engineers utilized VMware VirtualCenter 2.0.0 (Build 27704) on aseparate server. The VMware VirtualCenter afforded engineers the ability tocontrol and check the status of all ESX servers and Windows XP virtualmachines remotely and also allowed them to use a feature called VMotion thathelps to "migrate" (manually or automatically) virtual machines from one ESXServer to another in order to balance the VM load on each ESX Server.

For the storage environment, engineers utilized an enterprise-class storagesolution from IBM named IBM TotalStorage DS4500 (formerly FAStT900)that contained approximately 22 Logical Unit Numbers (LUNs) of 200GBeach, which in conjunction created a massive storage space available of4TB for the 17 ESX servers and 300 Windows XP virtual machines. Next,the network test bed environment was a full-mesh Gigabit Ethernet faulttolerant topology that interconnected all ESX Servers, storage areanetworks (SAN) and Windows XP virtual machines with an IBM FibreChannel switch that provided up to 1 GB full-duplex connection and CiscoCatalyst 4948 gigabit-speed switches.

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1 2 3 4 5 6 7 8 9 10 11 12 13 14

Citrix

Citrix

Citrix

Citrix

VMware

VMware

VMware

VMware

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VMware

OK

LOG TXRX

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2

1

TX/RX

Link

TX/RX

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TX/RX

Link

1

2

3

4

IBM BladeCenterblade servers running

Citrix PresentationServer

IBM FibreChannel Switch

CiscoCatalyst Switch

IBM Series x server runningVMware Virtual Center

IBM TotalStorage

IBM BladeCenterblade servers running

VMware ESX withWindows XP

To ta lSto rag e

DS4800

BladeCenter

1 2

CD CD CD CD CD CD CD CD CD CDCDCD

VMware

VMware

VMware

VMware

VMware

CD

VMware

VMware

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1 2 IBM BladeCenterblade servers running

VMware ESX withWindows XP

Catalyst 4948-10GE

PS1

STATUS

FAN

PS2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48CON MGT

X2-1

X2-2


FIGURE 2Test Environment



Citrix Presentation Server was configured to publish one application("RDPConnect") that invoked an automated script "user" which opened anICA session and called a process of Microsoft Remote Desktop Connection(mstsc.exe) in order to access a Windows XP virtual machine residing onone of the ESX Servers. If the user load evaluator defaults within CitrixLoad Management is enabled it only allows 100 simultaneous ICA sessionsper server, which led engineers to modify the setting to a higher number(1,000 sessions) in order to circumvent the imposed limitation.

Results and ObservationsCitrix Presentation Server Scalability withRemote Desktop Client

The first user scalability test scenario examined the scalability of a singleCitrix Presentation Server handling the session load between downstreamclients and back-end servers.

Tests revealed that the Citrix Presentation Server supported from 200 to 275simultaneous light-user sessions through a single blade server, betweendownstream clients and common office application running on the back-end servers with their virtual machine images. For the heavy-userscenario, Presentation Server supported up to 175 sessions through asingle blade server between clients and programming applications on theback-end virtual machine servers.

When engineers reached the maximum number of simultaneous usersessions, they recorded a snapshot of the Citrix Presentation Serverperformance using Microsoft's Perfmon (version 2.0) tool to measureprocessor usage, % disk time, average disk queue length, memory available,page faults per second, paging file usage and number of active sessions onterminal services. For more detailed information about these metrics, pleaserefer to Figures 3-4 on pages 12-13, and also refer to detailed results charts inAppendix B, on page 28.

Engineers found that the bottleneck for scaling beyond the noted ceiling inthe light-user scenario was the Citrix Presentation Server host machinehardware, specifically the local hard drive and page file location. Asshown in Figure 1, results show a high percentage of disk time (481%) -meaning that the buffer on the local hard drive is already overloaded withread or write requests from remote users which leads to an increase in the

10



elapsed time to provide read or write requests for new users. Whenpercent of disk time exceeds 100%, the hard drive becomes the bottleneckduring the performance testing.

Engineers subsequently moved the page file location from the local harddrive on the Presentation Server to an external logical drive located in theSAN. The size allocated for the page file was 20GB. Then, engineers re-ranthe light-user scenario with the modification and results showed that theCitrix Presentation Server was able to handle up to 275 simultaneous lightusers. At this peak, the percentage of disk time was only 11%, almost 44times less than with 200 simultaneous light users.

11

20 50 50 100 100 150 150 200 200 275

Page file on local drive

500

400

300

200

100

0

500

400

300

200

100

0

Page file on external drive

Number of simultaneous users2

(%) D

isk

time1

Comparison of the Percentage of Disk Time for a Light UserOperation over Citrix Presentation Server when a Page File isLocated on a Local Server Drive vs. an External Network Drive

as Reported by Microsoft Perfmon version 2.0

1 (%) Disk time is the percentage of elapsed time that the selected disk drive was busy servicing read or write requests from users. 2 Light and heavy user results represent data from different tests, the scenarios were not run simultaneously in one test.


FIGURE 3



This demonstrates that some amount of "tuning" should be possible tosqueeze greater scalability from Presentation Server in a virtualizeddesktop environment.

In the case of the heavy-user scenario, engineers found that thebottleneck for scaling up additional users was the processing powerprovided by the Presentation Server host device. As shown in Figure 4, at175 active sessions, the processor utilization was 98%. Nonetheless, theuser experience on all 175 heavy users was acceptable with no delays.

VMware ESX Server Functionality withWindows XP Guests

The user scalability test scenarios described above examined thescalability of a single blade server and System X server from IBM, handling

12

25 50 50 100 100 150 150 200 175 275

Heavy users

100

80

60

40

20

0

100

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40

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Light users

Number of simultaneous users1

CPU

Utili

zatio

n (%

) Heavy and Light User Scenarios

Measuring Processor Utilization (%) on Citrix Presentation Serveras Reported by Microsoft Perfmon version 2.0

1 Light and heavy user results represent data from different tests, the scenarios were not run simultaneously in one test.


FIGURE 4



two types of user workloads. Engineers also validated the use of differenthardware configurations on the blade server side and one high-end IBMSystem X server to host the Windows XP images under VMware ESX.

For the light-user scenario, tests were run on a single HS20 server bladeconfigured with two single core 3.8-GHz Intel Xeon processors and 4 GB ofRAM memory. Next, another BladeCenter HS20 blade server with the sameprocessing power as previously described, but with 8 GB of RAM memory,was tested. Finally, engineers tested the light-user scenario with an IBMSystem X3950 server with eight dual-core 3.0-GHz Intel Xeon processorsand 64 GB of RAM memory. The actual number of virtual machinesconfigured and used varied by server hardware configuration. An increasein the amount of physical memory — and the number of physical CPUs -increased the number of virtual machine guests that could be utilized.

Similarly, engineers tested the heavy-user scenario on each serverconfiguration. In all cases, VMware ESX was able to handle the incomingworkload with varied performance results. The actual number of guestoperating system instances that can be supported under VMware ESX isdependent on the hardware configuration, guest workload, andconfiguration of the ESX instance. Readers should access the VMware Website for current scalability and configuration information for VMware ESX.

Focus on Remote AccessPerformanceThe purpose of this testing was to measure the bandwidth and elapsed time ofa single "real" PC user executing different tasks (i.e. file open operations,remote printing and running a PowerPoint presentation) remotely on aWindows XP "virtual" image (from the VMware ESX Server) through the CitrixPresentation Server 4. Engineers utilized Spirent Communications IP Waveversion 3.0.0 Network Impairment Emulator tool to emulate three differenttypes of WAN connections: a DSL (1.544 Mbps/256Kbps) with 100ms of latency,a T1 (1.544 Mbps) with 50ms of latency and a satellite connection (512 Kbps)with 500ms of latency.

"File Open" Scenario

For this scenario, engineers ran an ICA session from the client PC to theCitrix Presentation Server. Once at Presentation Server, an RDP sessionwas established to connect to the Windows XP virtual machine.

13



During the "file open" session, engineers opened a Microsoft Worddocument (approx. 10 MB of file size) from the client PC and measured thebandwidth and times elapsed to page through and view the entire Worddocument. Engineers conducted the file open test over three WANconnections — a DSL (1.544 Mbps/256Kbps) with 100ms of latency, a T1(1.544 Mbps) with 50ms of latency and a satellite connection (512 Kbps)with 500ms of latency.

Engineers recorded two measurements — one for the "client" sideconnection, which was comprised of the ICA connection between clientand Presentation Server, and the other measurement was the back-endcorporate connection, which consisted of an RDP session fromPresentation Server to the IBM servers.

DSL ResultsEngineers first opened the 100-MB Word file across a DSL connection(1.544 Mbps/256Kbps) with 100ms of latency. Tests show that 49seconds elapsed between the time engineers first opened the file until they finished paging through to the file end. (See Figure 5.) What's interesting to note is that both the client-side portion of thesession and the back-end server portion of the session both served the file in the same time — meaning there was no inherent delayintroduced.

Readers should also note that the client-side of the session (client to Presentation Server) required 264 Kbps of bandwidth to handle the file open task, versus 748 Kbps for the back-end RDP-basedsession. That's because ICA employs very efficient compressionalgorithms that eases bandwidth consumption. Complete results arelisted in Figure 5.

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T1 ResultsEngineers repeated the test, this time over a T1 (1.544 Mbps) with 50msof latency. This time, the client-side connection served the file in anaverage of 48 seconds, while the server-side handled the file operationin 46 seconds. In terms of bandwidth consumed, the client-sideconnection required 259 Kbps while the back-end server connectionrequired 764 Kbps of bandwidth.

Satellite ResultsEngineers re-ran the test, this time over a satellite connection (512Kbps) with 500ms of latency. This time, the client-side connectionserved the file in an average of 72 seconds, while the server-sidehandled the file operation in 71 seconds. In terms of bandwidthconsumed, the client-side connection required 158 Kbps while theback-end server connection required 512 Kbps of bandwidth.

15

File Open Performance Results of RDP Protocol(Tunneled within ICA) Connection using Multiple Simulated Network Types

as Reported by Ethereal (ver. 0.10.13)

Network typesand latency

Etherealmeasurements

DSL(1.544 Mbps/256 Kbps)

— 100ms

T1(1.544 Mbps)

— 50ms

Satellite(512 Kbps) — 500ms

Iteration 1 Iteration 2 Iteration 3 Avg Iteration 1 Iteration 2 Iteration 3 Avg

File Open WAN (Client-side) File Open LAN (Back-end)— —

302

49

1,855,861

256

48

1,551,888

168

67

1,412,365

248

48

1,500,414

262

48

1,566,599

152

74

1,419,529

264

49

259

48

158

72

1,627,046

1,561,456

1,422,509

709

50

4,439,756

780

47

4,614,190

505

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4,691,194

774

48

4,658,561

756

46

4,406,682

533

66

4,391,712

762

48

4,592,327

756

46

4,383,239

497

73

4,567,412

748

49

4,563,548

764

46

4,468,037

512

71

4,550,106

241

50

1,524,864

260

48

1,565,881

155

74

1,435,634

Throughput (Avg. Kbps)

Time elapsed (seconds)

Bytes sent over the link








FIGURE 5



This demonstrates that, due to the sizable latency introduced over thesatellite link, the file was served in a greater amount of time, thoughless bandwidth was required to deliver it.

PowerPoint Scenario


Engineers then opened a Microsoft PowerPoint slide presentation (eightslides, 800 KB file size) from the client PC and measured the elapsed timeand bandwidth consumed to complete a slideshow. Complete results arelisted in Figure 6.

DSL ResultsTests show that 29 seconds elapsed to open and play the eight-slidePowerPoint presentation between the client PC and PresentationServer, while 27 seconds elapsed to serve the file across the back-endconnections stretching from Presentation Server and the backendservers.

From a bandwidth consumption perspective, the client-side connectionconsumed 206 Kbps to serve up the slide presentation, while thebackend server connection consumed 1.16 Mbps. This demonstratesthat Presentation Server is efficient at compressing large data streamsfor travel across WAN links.

T1 ResultsEngineers repeated the test, this time over a T1 (1.544 Mbps) with 50msof latency. This time, the client-side session required 26 seconds todisplay the slides, while the backend session required 25 seconds.

In terms of bandwidth, the client-side session consumed 218 Kbps,while the server-side connection required 913 Kbps.

Satellite ResultsEngineers re-ran the test, this time over a satellite connection (512Kbps) with 500ms of latency. The client-side session required 39

16



seconds to display the slides, while the backend session required 38seconds. Again, this demonstrates there was no introduction of delayon the server side of the task.

From a bandwidth perspective, the client-side session consumed 117Kbps; the server-side session required 932 Kbps. The higher bandwidthconsumption reflects the delay inherent with the satellite connection.

Remote Printing Scenario


Engineers then opened either a Microsoft Word document or a PowerPointPresentation (approx. 800 KB of file size) from the client PC and measuredthe bandwidth and time elapsed to print the complete document. Completeresults are listed in Figure 7.

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DSL(1.544 Mbps/256 Kbps)

— 100ms

T1(1.544 Mbps)

— 50ms



PowerPoint presentationWAN (Client-side)

PowerPoint presentationLAN (Back-end)

— —










220

30

842,821

208

27

717,424

120

38

576,439

190

30

719,612

227

25

715,275

111

40

565,674

208

28

734,087

218

26

727,351

119

39

581,250

206

29

765,507

218

26

720,017

117

39

574,454

1,080

27

3,661,132

969

25

3,088,381

878

36

3,999,174

1,244

28

4,413,854

942

24

2,841,934

916

39

4,466,031

1,230

27

4,110,373

827

25

2,594,644

1001

38

4,745,590

1,185

27

4,061,786

913

25

2,841,653

932

38

4,403,598

PowerPoint Presentation Performance Results of RDP Protocol(Tunneled within ICA) Connection using Multiple Simulated Network Types



FIGURE 6



DSL ResultsOver the DSL connection, with 100ms of latency, the client-side sessiontook 14 seconds to print the document, while the server-side used 12seconds. From a bandwidth perspective, the client-side session used717 Kbps and the server-side used 1.15 Mbps. The higher bandwidthconsumption on the back-end reflects the amount of data sent acrossthe link from the ESX Server to the Presentation Server. On the back-end, the compression is not as efficient as the compression offered byPresentation Server to the front-end link.

T1 ResultsEngineers repeated the test, this time over a T1 (1.544 Mbps) with 50msof latency. This time, the client-side session required 15 seconds toprint the file, while the backend session required 10 seconds.

In terms of bandwidth, the client-side session consumed 689 Kbps,while the server-side connection required 1.44 Mbps.

Satellite ResultsEngineers re-ran the test, this time over a satellite connection (512Kbps) with 500ms of latency. The client-side session required 30seconds to print the file, while the backend session required 11seconds.

From a bandwidth perspective, the client-side session used 345 Kbpsand the server-side session consumed 1.33 Mbps.

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Presentation Server Functionalitywith Virtualized DesktopsIn addition to the performance and scalability testing conducted by The TollyGroup, engineers conducted a thorough hands-on evaluation of five essentialCitrix Access Suite features relevant to the virtual desktop solution scenario.See Figure 8.

The purpose of this testing was to verify (pass/fail) each of the features using aWindows XP PC user. The remote user was first logged in to Citrix and thenstarted a remote desktop connection (RDP) to the back end Windows XPvirtual image then all tests were conducted. The features examined were:

Single sign-on

Auto-reconnect

Session reliability

Application management

Smooth roaming

19



DSL(1.544Mbps/256Kbps)

— 100ms

T1(1.544 Mbps)

— 50ms



Remote printingWAN (Client-side)

Remote printingLAN (Back-end)

— —










Remote Printing Performance Results of RDP Protocol(Tunneled within ICA) Connection using Multiple Simulated Network Types


719

14

1,291,573

626

16

1,304,508

358

28

1,278,270

676

15

1,305,326

755

14

1,301,075

330

31

1,311,352

756

14

1,309,688

686

15

1,295,632

347

30

1,301,449

717

14

1,302,196

690

15

1,300,405

350

30

1,297,024

9

1,110

12

1,734,814

1,653

2,001,263

1,176

12

1,736,113

1,238

13

1,997,643

1,264

11

1,737,249

1,447

11

1,999,417

1,182

12

1,733,245

1,497

9

1,735,647

1,454

11

1,997,324

1,176

12

1,821,901

1,471

10

1,824,720

1,360

11

1,910,951


FIGURE 7



Citrix Single Sign-on

Citrix Password Manager allows users to authenticate to the Windows XPdesktop without having to sign in multiple times. With the Single Sign-on,users do not have to enter the credentials each time they want to access aresource on Windows XP desktop either.

The RDP Client is published on the Citrix Presentation Server giving accessto the Windows XP desktop that is being virtualized by VMware ESX 3.0.By integrating the Citrix Password Manager agent as part of the virtualmachine image, users do not have to input their usernames and passwordsinto the RDP client and then again into the Windows XP login. The CitrixPassword Manager agent provides seamless integration throughout thelogin process and then also integration into the individual applications thatwould be present on the image itself (installed locally or published off ofCitrix Presentation Server).

By providing a single logon to all password-protected informationresources, Single Sign-on speeds authentication. It even enables users toreset their primary network passwords from their own PC, further reducingdisruption and the need to call the help desk.

In our hands-on evaluation, the agent was installed locally on the virtualmachine image and onto the Citrix Presentation Server. In the featuretesting scenario, Tolly Group engineers created an ICA file which providedpass through authentication throughout the login process when integratedin conjunction with Citrix Password Manager.

Auto-reconnect

The auto-reconnect feature allows users to re-establish an ICA sessionwithout user intervention. When there is an unintended disconnection ofan ICA session, this feature attempts to reconnect the user to the sessionuntil there is a successful reconnection or the user cancels thereconnection attempts.

In the feature testing scenario, Tolly Group engineers successfully verifiedthat even with RDP being used in conjunction with ICA, the test PC userwas able to reconnect automatically to the Citrix Presentation Serversession when there was no network connectivity. Engineers unpluggedthe network cable for 30 seconds and then plugged it back in again. Assoon as the client PC recovered network connectivity, the ICA session was

20



re-established automatically to the Windows XP desktop and applicationthat was being worked on.

Session Reliability

The Session Reliability feature allows users to maintain active ICAsessions even when network connectivity is interrupted. Users continue tosee the application they are using until network connectivity is restored.

One of the common problems with different access scenarios is that thequality of a network connection can never be guaranteed. Sessionreliability allows Citrix Presentation Server sessions to remain viewable onthe user's screen when network connectivity is interrupted. Users continueto see the application they are using until network connectivity resumeswithout reauthentication prompts.

This feature is especially useful for mobile users with wirelessconnections. If a user with a wireless link enters a railroad tunnel, orroams between different segments of a wireless network and momentarilyloses connectivity, the display on the client device freezes untilconnectivity resumes. The user continues to access the display during theinterruption and can resume interaction with the application when thenetwork connection is restored.

In this feature testing scenario, Tolly Group engineers successfully verifiedthat the test PC user was able to see the session open and active whenengineers unplugged the network cable for 30 seconds. Once engineersplugged the network cable back to the PC, the auto-reconnect feature re-established the ICA session showing the active session back to theWindows XP desktop.

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Application & User Management

This feature allows administrators to manage their user sessions andapplication deployment mechanics centrally through the Citrix AccessConsole in relation to virtualized desktops, published desktops andapplication publishing.

The advantage of using Citrix for application deployment as part of thisenvironment is the ability to integrate the Program Neighborhood Agentclient as part of the default virtual image. When a user connects to thebase virtual image, their credentials will be passed to the CitrixPresentation Server through the agent and those applications that theyhave access to will now be virtualized on the back end Citrix PresentationServer but the user will have all the benefits of being able to use theapplications as if they were installed locally on the image. This helpsadministrators in terms of deploying new applications, updates andpatches in this type of environment.

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Citrix MetaFrame Presentation Server 4.0 (Build 2198 Service Pack 2005.04) Enterprise Edition

FEATURES VERIFICATION

Type of features Description

—

Single Sign-on Pass-Through Authentication

Auto-ReconnectAutomatically reconnect to a session when the connection is dropped

Session ReliabilityKeeps ICA sessions active and on the screen when network connectivity is interrupted

Application & User Management

Allows administrators to publish specific type of applications or content to users through an ICA session

Smooth RoamingProvide users the capability to "roam" through multiple client devices and still be able to access the same applications or file content


FIGURE 8



Further, now administrators can view all the users as part of a singleconsole and manage them accordingly. Whether a user is connecting to apublished desktop, published application or pooled image, administratorshave the necessary control to effectively manage their farm of users,desktops and applications.

Smooth Roaming

This feature allows users to access their Windows XP from different client devices.

SmoothRoaming is a unique capability provided by the Citrix Access Suite.It allows users to move easily between access scenarios while maintainingthe same work environment. This allows a user to start working in onelocation, move to another location (or even on a different device ornetwork) and continue where they left off.

In the feature testing scenario, Tolly Group engineers successfully verifiedthat the test PC user was able access and remotely print a MicrosoftPowerPoint document through a virtualized Windows XP desktop fromcomputer A. Then, engineers logged off of computer A and they logged inon computer B. They accessed the same Microsoft PowerPoint documentin the Citrix Web Interface and they were able to print it remotely, as well.One item to note is that if client side printing is needed, the print driversmust be loaded on the Citrix Presentation Server in order for this to besuccessful. Network printers mapped without any issues. Also, in terms ofsmooth roaming, if different resolutions are configured on the client-sidemachines, a navigation toolbar appears since RDP is being used on theback end and ICA is being used at the client machine.

Virtual Desktop SuccessCitrix, IBM, and VMware have done well to architect a solution for virtualdesktop services, keeping the needs of enterprise buyers at the forefront of itsstrategy. Of course, Citrix Presentation Server also has the ability to publish aserver desktop which should fit the needs of most organizations. However, inthe use cases identified in this paper (offshore development, access toWindows XP corporate image, etc.) this is the reason why virtualizing aWindows XP desktop may be necessary.

From a scalability perspective, the Citrix and VMware solution demonstratesthat one Presentation Server instance can handle 200 light users and 175

23



heavy user sessions, and VMware ESX Server can be configured to handle acorresponding number of guest Windows XP instances.

On the remote access performance front, Citrix again has demonstrated thatits solution delivers more than adequate performance. Tests of PresentationServer handling file open, PowerPoint and printing operations across a virtualdesktop session, clearly demonstrate that Citrix's use of compression helpsorganizations limit the amount of WAN bandwidth consumed, while deliveringapplications through Windows XP desktops without delay.

Beyond scalability and remote access performance, Citrix delivers thefunctionality and features that help reduce the burden on IT supportorganizations. Support for single-sign on vastly simplifies the log-onauthentication for users, which lessens the burden on already taxed networkhelp desks.

Features like auto-reconnect and session reliability go to the heart ofapplication survivability. With auto-reconnect, should a session fail, thesoftware automatically attempts to reconnect the session until it succeeds orthe user aborts the session. And session reliability enables users to stay withan application; even when it temporarily interrupts due to a loss of signal orsession state. Users do not have to abandon a session because they know itwill rebound shortly.

Built-in facilities around application manager like the remote desktop brokerfurnish IT staffs with the tools they need to effectively manage desktop andapplication usage across the virtualized desktop environment. And facilitieslike Smooth Roaming offer seamless desktop services even as users roamacross a facility or hop from device to device.

In effect, Citrix, IBM and VMware deliver a virtualized desktop environmentwith a solid user experience (high performance over low bandwidth andSmoothRoaming), a secure infrastructure (Single Sign-on, SSL support andpolicy-based access), a proven management infrastructure (load balancing,resource management, connection policies) and flexibility (basically any virtualmachine can access services when needed).

24



Appendix A. Scalability TestMethodologyEach ICA session created used the default settings; however, the Windowsproperties were set as follows:

Window Colors: High Color (16-bit)

Window Size: 1024 x 768

Similarly, the RDP sessions created through Citrix Presentation Server weremodified with the following settings:

Display Tab

Remote Desktop Size: Full Screen

Colors: High Color (16-bit)

Local Resources Tab

Remote Computer Sound: Do not play

Local Devices: Disk drives, Printers and Serial ports (all unchecked)

For the VMware ESX Servers, engineers enabled VMware DistributedResource Scheduler (same as VMotion) in order to migrate or move WindowsXP virtual machines from one ESX server to another in order to balance theload on each ESX server to avoid possible overloading. By default, the VMwareESX Server has 24 ports available for the virtual switch device that allowsvirtual machines and ESX servers to communicate within a "virtual" network.The number of ports was modified to 500 ports by engineers since they weredealing with a high number of virtual machines (300) and it was seen that thepowerful IBM System X server (Model x3950) was capable to handle up to 100virtual machines simultaneously.

For the Windows XP virtual machines installed on all 17 ESX servers, they allwere outfitted with a full version of Microsoft Windows XP Professional withService Pack 2. For the light-user scenario, each virtual machine was assignedwith 256 MB of RAM and for the heavy-user scenario with 512 MB of RAM.There was no limitation on processor usage from the ESX Server. In addition,engineers modified the Power Options settings to be "Always On" and disabledthe screensaver. Once all the settings were modified on a single Windows XPvirtual machine, engineers cloned that virtual machine 299 times in order tohave the same virtual machine for all the users.

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For the script users, engineers used AutoIt version 3.0 in order to simulate twoclasses of users: light and heavy users. For the light-user scenario, engineerscreated a script that opened Microsoft Word and started typing "The Bill ofRights" (the first 10 amendments of the U.S. Constitution). Character data wasentered every 100 milliseconds in order to simulate human typing speeds. Oncethe entire document was done, the script saved the file(s), and then opened anew document on Microsoft Word and started all over again. For the heavy-user scenario, engineers created a script that opened Microsoft Visual Studio2005 and started typing standard mathematical formulas such as logarithm,square root, addition, subtraction, power formulas and others that ultimatelywere compiled and executed. Once again, engineers added a delay of 100milliseconds for every character typed to simulate human typing.

For the script automation, an executable program was created by engineers toallow them to run multiple instances of Citrix ICA sessions with a delay time inbetween each session to avoid overloading on the Citrix Presentation Serverand conflicts on the client machine. The delay time allocated was 30 secondsfor the light user testing and 60 seconds for the heavy user. Next, a batch filewas created by engineers in order to call the AutoIt script that simulates thelight user and heavy user scenario. The batch file was placed on the startupfolder on all Windows XP virtual machines, so it can be executed once thescript user (light or heavy user) logged into the Windows XP virtual machine.

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Appendix B. Scalability Test Results,Detailed Charts

27

No. of users

% Disk time(logical disk)

Avg. diskqueue length(logical disk)

AvailableMbytes

(memory)

Pagefaults/sec(memory)

% Processortime (processor)

Activesessions

% Usage(paging file)

25

50

100

150

200

13.43 0.134 6433 72.025 9.423 1.563 20

61.58 0.616 5605 1089.955 15.801 8.594 50

13.074 0.131 3941 169.474 24.578 23.81 100

311.348 3.113 3223 531.104 4.448 32.032 150

481.477 4.815 3806 381.131 23.448 40.295 200

Light User Results with Page File Located on Local Drive of Citrix Presentation ServerAs Reported by Microsoft Perfmon version 2.0


FIGURE 9

No. of users



AvailableMbytes

(memory)


% Processortime (processor)

Activesessions

% Usage(paging file)

0 0 6046 155.996 1.355 5.86 50

1.65 0.033 4673 434.982 2.767 15.631 100

0.655 0.013 3388 218.976 4.159 19.917 150

0.97 0.019 2024 692.828 5.466 35.157 200

31.724 0.634 680 1042.394 6.816 47.786 250

50

100

150

200

250

275 11.22 0.224 484 761.879 N/A 67.691 275

Light User Results with Page File Located on External Logical Drive in Storage Area Network (SAN)As Reported by Microsoft Perfmon version 2.0


FIGURE 10



Heavy User Results with Page File Located on Local Drive of Citrix Presentation Serveras Reported by Microsoft Perfmon version 2.0

No. of users



AvailableMbytes

(memory)

Committedbytes

(memory)


% Processortime

(processor)

Pages/sec(memory)

Activesessions

% Usage(paging

file)

25

50

100

150

175

0

2.44

6.75

17.13

40.722

0

0.024

0.067

0.171

0.407

6,574

5,885

4,447

3,085

2,382

1,530,990,592

2,568,597,504

4,695,183,360

6,735,712,256

7,768,895,488

741

1,705

887

3,445

3,484

1

1

0

1

12.267

1.321

2.123

4.578

6.134

6.967

12.501

15.626

37.891

81.562

98.077

25

50

100

150

175


FIGURE 11



Appendix C. Virtual MachineBreakdown

29

Virtual Machines and Associated Performance Attributes Observed on IBM Blade Servers

Load scenario Server model No. of userssupported

Measurements

AverageCPU utilization (%)

Averagememory usage (%)

BladeCenter HS20CPU type: Intel Xeon (single-core)No. of CPUs: 2/2 (physical/logical)CPU speed: 3.8-GHzRAM: 4 GB




IBM System X3950CPU type: Intel Xeon (dual-core)No. of CPUs: 8/16 (physical/logical)CPU speed: 3.0-GHzRAM: 64 GB

Light

Heavy

11 14.53 33.6813 18.40 40.3315 27.39 54.5918 31.53 61.8320 36.34 69.0425 44.83 81.86

10 32.94 54.2215 34.10 51.1720 37.23 48.0825 42.48 49.4230 50.78 57.2935 63.15 72.6040 75.34 83.89

80 20.94 41.60

100 30.02 42.30

10

12

15

20

44.01

46.52

49.48

53.97

66.26

69.87

73.33

77.28

10

15

20

25

16.71

22.36

34.99

49.43

20.82

27.88

43.27

58.96


FIGURE 12



Appendix D. Scalability Testing Tipsfor a Virtual Environment usingVMware ESX ServerThe following information was created based on the testing experience gatheredduring the user scalability testing in IBM's lab in Kirkland, WA.

1) When installing Windows XP operating system virtual image(s) or newerversions, it is recommended to run the Windows Product Activation(WPA) process in order to avoid any processes running on the clientvirtual machine reminding the client(s) to activate their product. Thesame applies to the operating system where Citrix Presentation Server isinstalled otherwise the system consumes most of the memory on the WPAprocess for each ICA session.

2) Disable screensavers.

3) Modify the Power Options of Windows to be set at "Always On" for the virtualdesktop and set no password for the administrator or profile that you areusing for the testing.

4) Move the Page File to a secondary drive or external drive to avoid any delayon read/write requests for the remote users.

5) When encountering a Windows error message on the virtual machine's EventViewer with Event ID: 50 "The RDP protocol component "DATA ENCRYPTION"detected an error in the protocol stream and has disconnected the client."

Please refer to the following link to fix the issue:http://support.microsoft.com/kb/323497/en-us.

6) Enable VMware DRS (VMotion) feature in "Manual" or "Fully Automated" butset as "Conservative". Otherwise disable this feature. That way, errors on thevirtual machine file system will be avoided.

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http://support.microsoft.com/kb/323497/en-us

Information technology is an area of rapid growth and constant change. The Tolly Group conducts engineering-caliber testing in an effort to provide the internetworking industry with valuable information on current productsand technology. While great care is taken to assure utmost accuracy, mistakes can occur. In no event shall TheTolly Group be liable for damages of any kind including direct, indirect, special, incidental, and consequentialdamages which may result from the use of information contained in this document. All trademarks are theproperty of their respective owners.

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