ESXi

System

quad Xeon 7540 (4 processors, 6 cores on each)

ESXi 4 Single Server (free version, should support 4 processors and up to 6 cores per cpu)

Hyperthreading enabled

In the vSpere Client the hypervisor level reports 4 processor sockets, 6 processor cores per socket, 48 logical processors so all looks good.

VM

I created a linux RHEL 4.8 AS VM

I want to run just the one main VM on the server so I would like to assign the bulk of processing power to this VM

In the VM properties page I can only set it to 4CPU's with the free license so I set it to 4

Benchmarks and /proc/cpuinfo suggest it's not using any multiple cores, performance monitor just shows 4 cpu's (not sure if it should report hyperthreaded cpu's separately?)

CPU/MMU Virtualization set to Automatic

Problem

The guest VM does not appear to be accessing the full 48 logical processors available at the hypervisor level. Is there somewhere where I can set the number of logical processors to be used by the VM? In linux I can only see 4 cpu's and no sign of hyperthreading or amazing performance. Should /proc/cpuinfo be telling me more about each processor? How do I know what the VM is actually seeing/using? Any clues?

Thanks for any tips

Hi,

If you only assign your RHEL Virtual Machine 4 cpu's, it will only see and be able to use 4. Hyperthreaded cores are seen as an individual core presented to the virtual machine.

If you want to make use of more cpus then use the paid for ESX to get 8 CPUs or if you are only planning on using that one guest on the host and you need it to use all cpus then you will need to just install Red Hat direct onto the box and not virtualise it.

Hope this helps,

Dan

I'm confused because the spec sheet seemed to say that the free version would support 4 sockets with up to 6 cores per socket. It didn't say anywhere that there is a limit of 4 of these virtual processors to each VM.

So is it the case that although the free single server version supports and can see 48 virtual processors (using hyperthreading) there is a limit of 4 per VM?

thanks

Welcome to the Forums - yes that is a constraint of the Free License you will only be able to create VMs with 4 vCPUs which can only be scheduled to a single LCPU at a time - if you want to invest in the Enterprise Plus license you then will be able to create a VM with 8 virtual CPUs utilizing 8 LCPUs at a time - the vm can be scheduled on any of the 48 LCPUs but it will only use as a maximum 8 at a time -

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The free version does support up to 4 cores per socket. However, the documenation is very clear that no VM (under the free version) can be more than 4 vCPUs. Even the highest paid version does 8 vCPUs per VM.

There is no way to assign more than 8 cores to 1VM - if you want to dedicate most of the power of this machine to one host, why not go natively installed?

--Matt

VCP, vExpert, Unix Geek, Storage Nerd

If you check out the Configuration Maximums Doc from VMware here: http://www.vmware.com/pdf/vsphere4/r40/vsp_40_config_max.pdf

It breaks it down into the maximums for ESX hosts which is your total physical cpus and cores and then the Virtual Machine maximums, the virtual CPUs or Logical CPUs.

However if you really need the full resources of that box, I would just install straight on to it without virtualising. (I hate saying that!)

Many thanks. I hadn't come across that table before. I'll scrub the install and just install RHEL on the box.

I thought I might be able to piggy back some other test servers onto the machine but I don't want to do that at the expense of the main machine performance. I think I'll have another box drop out of the system that I can install ESXi on and do that.

Cheers

It sounds that a bare-metal hypervisor is not the appropriate choice then, but you could install vmware server within RHEL

It might be worth looking at the workloads destined for the RHEL OS though. IMO it is not that common for a workload to be able to benefit from 24-core concurrency on it's own.

http://blog.peacon.co.uk

Please award points to any useful answer.

Thanks, I have installed RHEL 4.8 on the beast and I'll have a look at installing vmware server to run a guest rhel 5 server.

It's a build server so it's pushed hard for a few hours a day... build time down from 4 hours to about 40 mins apparently. Cool.