Citrix on VMWare ESX

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Although these guidelines are created using the following environment, these standards should apply to just about any Terminal Services-based virtual environment (XenApp 5, Quest vWorkspace 6, 2X, Windows 2008 TS, etc.):

• VMWare ESX 3.5 Update 2
• Virtual Center 2.5
• Windows 2003 R2 SP2 Standard Edition
• Citrix Presentation/XenApp Server 4.5

Virtual Machine Settings

• 1 vCPU
• 2 GB RAM
• HDD1: 15 GB vmdk on VMFS (used for OS)
• HDD2: 15 GB vmdk on VMFS (used for data, increase as necessary)
• Delete the CD/DVD and FLOPPY drives from the VM
• Disable Sound
• VMTools: Do NOT install the Balloon Driver

Virtual Machine, Operating System

• Windows 2003 R2 SP2 x86 STANDARD
• Latest service packs and critical updates
• 6 GB Page File on Data Drive
• Disable any unused services
• Citrix Presentation Server/XenApp Server 4.5 RollUp 3
• Standard applications & toolsets

Further explanations & considerations:

• Create a template, then deploy from a SysPrep'd Template. The template should follow best practices, including aligning the drives, registry settings, etc.
• Windows will scan the CD and Floppy drives, even if they are empty, by removing the drives, you reduce OS overhead. These can be added back later when needed, but when virtualizing, every little bit helps.
• Not installing the balloon driver (knows as the Memory Controller in the install set) will reduced the memory swapping which wreaks havoc on Citrix in a VM environment.
• Because of I/O demands, placing the VMDK files on a RAID10 set is optimal.
• Consolidate similar workloads where possible, i.e., have a cluster of ESX hosts dedicated to ONLY your Citrix Farm. This will optimize VMWare's native memory sharing as well as streamlining I/O.

Finally, as a general Rule of Thumb 2 Citrix VMs = 1 Physical Citrix Server. Obviously, this will vary based upon the actual workloads and application demands. As your farm grows, Scale out, not up…

Additional Reading:

• For more info on templates and other settings, see my other article on VMWare Best Practices.
• Vincent Vlieghe's most excellent article, detailing many of these settings.
• The Ether's take on optimizing Citrix on ESX