Citrix on VMware, 1vCPU or 2vCPU ? at 22:15

Following my previous Citrix testing on VMware I thought it best to try a dual vCPU VM to see if I can get double the users of a single vCPU, sounds logically sensible to me !

So just a reminder that a single vCPU with 25 users ran at around 73% average, a nice figure to run at giving plenty of CPU for peaks and troughs.

This test of a dual vCPU was undertaken following the sucesfull test of 25 users on one VM with 1 x vCPU this was run as a baseline to see how it relates to the single vCPU VM.

Virtual Machine Specification

2 x vCPU (Using VMware process affinity to tie the VM to a specific CPU core)
3072 GB RAM (reduced from 4GB as memory was not being used)

1 x 20GB Hard Disk Stored on SAN

1 x vNic (1GB)

Users Logged on: 50

• Logged 10 users on and working over 5 minutes
• Logged another 10 users on and working over 5 minutes
• Logged another 5 users on and working over 3 minutes
• Kept 25 users logged on and working for 15 minutes
• Logged all 25 users off over a 5 minute period

As you can see from the above, a 3000Mhz server runs at around 60% which is not a good start bearing in mind the single vCPU VM.

Next Test 50 Users and Dual vCPU

This test was undertaken following the sucesfull test of 25 users on one server with 1xVCPU allowing for a reasonoble amount of capacity for application usage.

Virtual Machine Specification

2 x vCPU (Using VMware process affinity to tie the VM to a specific CPU core)
3072 GB RAM

1 x 20GB Hard Disk Stored on SAN

1 x vNic (1GB)

Users Logged on: 50

• Logged 20 users on and working over 5 minutes
• Logged another 20 users on and working over 5 minutes
• Logged another 10 users on and working over 3 minutes
• Kept 50 users logged on and working for 15 minutes
• Logged all 50 users off over a 5 minute period

The peak CPU usage of this graph was reached before 50 users were connected and therefore proves that the best method to get more users per physical server is to scale out rather than increase CPU resources.

This will obviously make sense in some cases where the cost of Operating System, Application software and licenses and management costs may make sense to build a 2 x vCPU and get slightly more users.