A Review of XenApp 6.5 Scalability
As a Technical Relationship Manager, I spend a lot of time researching the more complex questions asked by customers that do not fit into the traditional Break-Fix reactive support model. One that I was asked recently sparked a good bit of thought, research and a debate within the TRM Team at Citrix and I wanted to share my findings.
The customer question was: What is Citrix’s recommendation for the maximum number of servers, users etc for a XenApp 6.5 Farm?
There are some published documents that discuss XenApp 6.5 Farm scalability which you can read here:
Planning Server Functions: http://support.citrix.com/proddocs/topic/XenApp 6.565-planning/ps-planning-infrastructure-servers-v2.html
XenApp 6.5Enterprise Scalable XenApp 6.5 Deployments: http://support.citrix.com/article/CTX131102
Speeding up Farm Deployments with XenApp 6.5– Part 3: http://blogs.citrix.com/2011/09/23/speeding-up-Farm-deployments-with-XenApp 6.5-6-5-part-3/
Pedal to the Metal: Bare Metal Scaling of XenApp 6.5 Hosted Shared Desktops: http://blogs.citrix.com/2013/03/28/pedal-to-the-metal-bare-metal-scaling-of-XenApp 6.5-6-5-hosted-shared-desktops/
After reading these documents I drew a these conclusions:
- The largest XenApp 6.5 deployment we have tested internally was 1000 servers in a single Farm.
- Memory consumption of the IMA Service on the Zone Data Collector is going to be a critical bottleneck as Farm size increases.
- It is the fine detail of how the Farm has been deployed and how it is used that will determine overall scalability.
GENERAL FARM LIMITS
We recommend no more than 5 zones per Farm due to the mesh network nature of Zone Data Collector communications – adding zones exponentially increases the network chatter and bandwidth required to maintain inter-zone communications. I wrote about this a couple of years ago here: http://blogs.citrix.com/2012/11/26/some-XenApp 6.5-6-5-Zone Data Collector-replication-calculations/.