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© 2012 Citrix | Confidential – Do Not Distribute
Introduction
• Why did you create a best practices
document?
• What is a best practice anyway?
ᵒ Appropriate at least 80% of the time
ᵒ Provides a good starting point
• Where do the best practices come from?
ᵒ Lessons learned
ᵒ Engineering
ᵒ Testing
ᵒ Customer feedback
Desktops
Users
Applications
Personalization
Access
Hardware
Control
© 2012 Citrix | Confidential – Do Not Distribute
#1: Scale Up or Out?
• There are many components: ᵒ Hardware & appliances
ᵒ Infrastructure servers
ᵒ XenApp servers
• There’s a lot to consider: ᵒ Available space
ᵒ Cooling & power capacity
ᵒ Hardware & maintenance costs
ᵒ Single points of failure
ᵒ Too many eggs
© 2012 Citrix | Confidential – Do Not Distribute
#2: Hyper-threading
• Allows single physical processor to appear as two
virtual cores
• Can increase user density per VM (XenApp) and
VM density per host (XenApp and XenDesktop)
• Typical performance boost of between 20-30% -
NOT 100%!
• My not be beneficial in every situation – will
depend on workload
© 2012 Citrix | Confidential – Do Not Distribute
#3: Processor and Memory Overcommit
• XenApp ᵒ Users per core – 30 [Light], 15 [Medium], 7 [Heavy]
ᵒ 1 to 1 mapping between vCPUs and cores
ᵒ Don’t overcommit memory
• XenDesktop ᵒ Users per core - 10 [Light], 6 [Medium], 2 [Heavy]
ᵒ Careful when overcommitting memory (5-10%)
• Don’t forget the hypervisor!
© 2012 Citrix | Confidential – Do Not Distribute
#4: XenServer Pool Design
• Separate resource pools for: ᵒ Control infrastructure
ᵒ XenDesktop
ᵒ XenApp
• Maximum pool size: ᵒ 16 hosts without single image technology
ᵒ 12 hosts with PVS
ᵒ 8 hosts with MCS
• Redundancy ᵒ Enable HA
ᵒ Specify multiple servers in host connection
© 2012 Citrix | Confidential – Do Not Distribute
#5: XenServer 6.02 Optimizations
• Use processors that support nested paging and second level address translation – ᵒ Extended Page Tables (Intel)
ᵒ Rapid Virtualization Indexing (AMD)
ᵒ “Optimize for XenApp” was essentially a software implementation
• Disable power saving (Green IT) functions in BIOS
• If you have more than 50 VMs per host - increase DOM0 RAM from 752MB to
2.94GB
• Receiver Side Copy (RSC) ᵒ Enabled by Default
ᵒ Work offloaded from DOM0 to guests (increases DOM0 scalability)
ᵒ Disable for small number of network intensive VMs (e.g. Provisioning Services)
© 2012 Citrix | Confidential – Do Not Distribute
#6: Storage Best Practices
• Storage is a very complex topic ᵒ CTX118397 – Introduction to Storage Technologies
ᵒ CTX130632 – Storage Best Practices
• Make sure you understand the requirements ᵒ Storage space vs. Speed
ᵒ Track the respective Win/XS performance counters • i.e.: Physical Disk \ Disk Transfers/sec = IOPS
• Monitor disk latency at all times ᵒ <10ms = OK / 10-20ms = Warning / >20ms = Issue
© 2012 Citrix | Confidential – Do Not Distribute
#7: License Server Redundancy
• Typically a single Citrix License Server is
sufficient ᵒ Grace period of 30 days
ᵒ 5 second delay for new user sessions
• Provisioned XA servers are an exception ᵒ Licenses are cached within a local ini-file
ᵒ ini-file is updated on IMA startup
• CTX131202 describes how to redirect the ini-
file to a network share / persistent disk
© 2012 Citrix | Confidential – Do Not Distribute
#8: Antivirus Optimizations
• Optimizing AV for a virtual desktop environment is
a must.
• Follow the recommendations outlined in
CTX127030
• In addition ᵒ Disable scheduled scans (i.e. upon pattern retrieval)
ᵒ Test new pattern before rollout / stagger the rollout
© 2012 Citrix | Confidential – Do Not Distribute
#9: PVS Ports & Threads
• By default PVS uses ᵒ 20 TCP ports for streaming
ᵒ 8 Threads per port
= 160 Threads
• Every target device uses one thread
when reading from its vDisk
• No thread available = queuing = disk latency
• # of ports” x “# of threads/port” = “max active clients” ᵒ Consider HA scenarios
© 2012 Citrix | Confidential – Do Not Distribute
#10: Various Items
• Have a proper monitoring solution in place ᵒ Monitoring Guide is coming soon
• Perform Capacity Planning
• Implement a three-staged test environment at minimum ᵒ Dev/Test
ᵒ UAT
ᵒ Pre-Production
ᵒ Production
• Develop/Implement Change Management procedures
• Backup your environment / perform restore tests
© 2012 Citrix | Confidential – Do Not Distribute
Summary
• We’re constantly refining the document ᵒ Subscribe to the Citrix KB RSS feed
ᵒ Subscribe to the XD Handbook (http://bit.ly/xdhandbook)
ᵒ ..or check CTX132799 every month or so
• If you have feedback / suggestions drop us a mail ᵒ Andy Baker ([email protected])
ᵒ Thomas Berger ([email protected])