How many VMs per ESXi?

[lark_90]

Hi,

Is there any calculator to give an estimate of how many VMs (2 vCPU/4G memory) can be run in their full capacity simultaneously on a ESXi 5.5 Host (without any fail-over consideration that is no DRS and no HA) with the following detail:

Dell PowerEdge M630

36 CPUs x 2.294 GHz

2 Processor Sockets

18 Cores per Sokect

72 Logical Processors

524GB RAM

This is for visualizing Kiosks estimation.

Thank you 

[daphnissov · Accepted solution]

What is the definition of "full capacity"? Based on a pure allocation model with no overcommit, you can get about 18 VMs out of that system (CPU most constrained) which doesn't account for any ESXi overhead.

[lark_90]

Thank you. This means that basically one VM per core.

By "full capacity" i mean maximum usage of CPU and RAM for each VM (each VM is a public kiosk).

[Mathieu_C]

It depend the CPU usage of your VMs and the performance do you want to have (Production or Test) who choose the Overcommit.

The monitoring and the design are very important !

Generally overcommit ratio of 3 for production, 2 for agressive VM and 1 for very sensitive production, after that you just check the CPU usage of ESXi generally must be lower than 50% and after the CPU ready of the most used VM of each hosts.

[lark_90]

Very interesting, thanks. Is there any VMware document explaining these in particular?

[jchilton]

Great article here from Dell https://communities.vmware.com/servlet/JiveServlet/previewBody/21181-102-1-28328/vsphere-oversubscri...

3:1 vCPU to pCPU ratio could be possible depending upon workload in your environment. So i read it from your servers that if hyperthreading is enabled you could have 72 pCPU so up to 200 vCPU could work....