i have a doubt on how actually the limit is set on the total number of VCPUS that can be assigned to a vm running on a server with ESX.does it vary with the number of cores and hyperthreading that comes with the host server?can someone help me on this.am trying to get a clear picture on this concept.
The limit is 4 vCPUs.
In theory it has nothing to do with the number of cores or hyper threading in the host.
In practice it does since the scheduler needs enough "free" physical cores to schedule the VM.
For example it is a bad idea to run two quad-vCPU VMs on a host with only four cores.
as the other poseter said it has nothing to do with # of cores or hyperthreading - and if you do decide you need to create a virtual SMP make sure you have at least twice the number of cores as the most vcpus you will use - best practice though is to start with uni vcpu vm and more cpus if needed because due to the way the vcpus are scheduled can cause a performance hit to the vm -