CPU count confusion

[TejVM]

Hi,

We have below specification for one ESXi host.

HP Proliant DL 580 G7

  CPU Cores 12 CPU x 2.399 GHz

  Processor Socket 2

  core per socket 6

  logical processor 24

Now how many VMs can create on this host and how many CPU we can assign,? How can we calculate how many CPU's are currently assigned and in use?(please refer atachment)

Thanks

[weinstein5]

Welcome to the Community - How many VMs a host can handle depends on the workload the VM s will have - depending on license level of your ESXi lisense will determine the maximum vCPUS per VM - the highest license allows you to create 32 vCPUs  all the other licenses I believe th mac is 8 VCPUs per VM - The ESXi host will use all CPUs it had access to scheduling VMs as needed.

PLease note VMware best practitice is always to start with a single vCPUand if you do need more than a single vCPU move up slowlky starting with 2.

Looking at you host and assuming you have sufficient  memory, network and storage  you should be able 180 to 200 VMs on this host

ALso I am moving this to a more appropriate forum -

[TejVM]

Thanks a lot !!!

Maximum 8 vCPU I can assign to each VM. But my query is as per above specifications of host how many CPU (say 24 or 48 or like that) can be assign? Currently I have assigned 34 CPU's on one esxi host which has above same configuration?

[weinstein5]

You do not 'assign' the physical cpu you allow the ESXI hosts's vmkernel to schedule the VM vCPU to run on a physical CPU - with vSphere 5 and typically loading you can have 8-10 vCPU per physiclical or logical CPU - so with you configuration dual 6 core cpus and hyperthreading enabled you will have 24 (6x2x2) LCPUs and should theoretically be able to have 192-240 single vCPU VMs assuming you have sufficient memory, stprage and network =

[Ravi_V]

Only vCPUs are assigned. Think of this as thin provisioning for CPUs. If you have 100 VMs having 1 vCPU each with 10% utilization, you are good, since you are at 41.67% on the host. If each VM suddenly needs 25%, it will not be possible, since this resource is now oversubscribed. The answer to your question is - It depends on the workload. Start with a decent number of VMs and plan to add incrementally until the utilization is fairly high while still retaining some room for peaks.

[EvanSoon]

Does this means that we would not be able to determine how much remaining vCPU we could assign and would only be able to estimate?

Lets say I have 48 Logical Processors and I am only using about 8% of it as of current. Is it safe to say I could make about 10x the current amount of VMs with the same amount of vCPU and reach a 80% usage?

I am also a little confused with the total amount of vCPU we could assign in a box. Do I need to reserve 50% of the total amount for HA like what I need to do for Memory?