Speccing Out a New ESXi 5 Server

[MikeGIllinois]

I want to put together a new ESXI 5.x server for a client and would like to clarify some points, if I may.

1. ESXI 5.x supports up to 32 gigs of RAM, correct?

2. If I have a server with one quad core processor I have, from ESXI's point of view, four available CPU's to allocate to virtuals, correct? And if I had two quad-cores I'd have 8 CPU's to allocate to virtuals?

With ESXI 4.1 I have found that two logical CPU's work just fine supporting a heavily used CPU on a new HP server as long as my other virtuals are low demand virtuals like data storage servers or Symantec Anti-Virus servers, etc.

3. I did ask earlier but it's not kosher to overallocate CPU's it? If I have a quadcore processor and assign 8 CPU's to virtuals I'm overallocating. Is that still a bad thing with 5.x?

Thanks much for the continued friendly help I get out here.

Mike Gallery

[a_p_]

1. It's only the free Hypervisor edition which is limited to 32GB physical memory. However, even the low priced Essentials Edition will not only remove this limitation, but also unlocks the API to allow e.g. image based backup applications. Never forget backup when designing a solution.

2.+3. Overprovisioning is not a bad thin per se. It depends on the workloads and how you configure the VMs. In most environments I built, the CPU is overcommitted and I didn't have any issues with this so far. When you take a look at the CPU usage on a typical ESXi host, you will notice that host CPU isn't used as much as you would expect.

André

[MikeGIllinois]

Thanks so much for your reply. I do backup in one form or another. If the computer is relatively static I'll backup the .vmdk. Otherwise I use Windows Backup.

Is my understanding correct here?

2. If I have a server with one quad core processor I have, from ESXI's point of view, four available CPU's to allocate to virtuals, correct? And if I had two quad-cores I'd have 8 CPU's to allocate to virtuals?

Thanks for your help and comments on overprovisioning.I opened a thread in the ESXi 4.x forum about this and was told that it's always bad and can cause lots of problems. I guess that's not the case anymore, or never was?

Mike

[a_p_ · Accepted solution]

As for the backup, you can certainly manually backup or use in guest backup like Windows Backup. I just wanted to mention it because a lot of people don't think of this.

Regarding provisioning, it depends on the workload like I mentioned before and also depends on how you configure the VMs. If you have one 4 core CPU and configure the VMs with 4 vCPUs you may soon run into issues. However, if you configure the VM's with 1 vCPU (or maybe two for individual VMs) it might be possible to run 10 VMs or more without issues. Whatever you do, remember that the host also needs some resources.

André

[Cyberfed27]

Remember that VMware is handling the management of physical resources. In your example if you have 2 sockets with 4 cores VMware will list it as 8 processors available. That doesn't mean if you assign 2vCPUs to a VM that you only have 6 left and then you 'run out'.

VMware is providing slices of time on the physical hardware for all of your VM's to run on.

As best practice we always start off our VM's with the least amount of resources and only increase the vCPUs and/or memory if needed. If you are running Windows 2008 or higher it has no trouble adjusting to the CPU/Memory changes. That way you are not assigning more resources that is actually needed. Many physical servers have way more resources than they need to begin with and replicating that in a VM environment is wasteful in my opinion.