Building large VM for SQL 2008 Enterprise

[livedrive777]

I was planning on building a large VM environment for SQL 2008 Enterprise. I only just realized that the maximum number of vCPUs you can assign to a VM is 8 based on this document:

http://www.vmware.com/pdf/vsphere4/r41/vsp_41_config_max.pdf

As I understand it each vCPU corresponds directly to a single core on the physical processors. Does this in turn mean that the maximum processing capacity I can get for a single VM is the equivalent of 2x quad core processors (8 cores = 8 vCPU) or is there another way to work it so that I can get more than that?

I'm concerned about this particular SQL environment needing more processing capacity than 8 cores/vCPUs.

Ideas? Or do I have to take this environment out of VMware and deploy physical?

[weinstein5 · Accepted solution]

No 8 is the maximum number of vCPUs you can assign to a VM - As much as VMware would like to say all workloads can be virtualized there are ones out there that might not be able to good candidates for virtualization and possibly your SQL server might be one of those. With that being said, in my experience, I have not come across many SQL servers that can not e virtualized.

What makes you say that thei SQL server needs more than 8 cores?

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[livedrive777]

I don't know for certain that it does, but I don't want to find myself in the position where we have to grow the environment and then are significantly limited. Maybe it is worth it for now and then just expect that VMware will soon support more vCPUs in the near future.

Am I correct in stating that each vCPU can only be assigned to each processor core? (You can't assign a vCPU to a single socket with all of its cores or something like that can you?

[thakala]

You are correct, single vCPU can only utilize single core at a time.

It is rumoured that next major vSphere release will support 16 vCPU VMs, but you need lots of cores on single pCPU to benefit much of that. If you run 16 vCPU VM on modern quad socket system with quad core CPUs your NUMA locality will be very poor and performance may not be what you expect.

Tomi

http://v-reality.info

[Cyberfed27]

I had this problem, well sorta as well. I was considering going VM on our SQL DB servers.

We decided against it for a few reasons.

1. We currently have 4xQuad Core CPU's = 16 cores total and the server is actually using them all, yes the DB processes THAT much data! Plus the DB servers have 128GB RAM.

2. If you were to virtualize it and give it the max of 8 cores, unless you have a real powerhouse of physical hardware, you are going to assign most of the vmhost's physical resources to it anyways, leaving you little room to add other VM's on that host.

Then of course if you want to do vMotion or HA, your other vmHosts will also have to be able to meet the resource needs of this virtual DB server.

I guess it depends on how realistic it is for your DB server to actually use 8 cores + RAM.

[livedrive777]

Thanks for the feedback everyone. I decided to move forward with the virtualized environment. We expect a slow ramp up of this environment over time, so I can adjust as needed or as new tech becomes available. My primary concern was getting boxed into a configuration that would be too limiting, but I think the VM is still the best environment for us overall. I will prob start with 4x vCPUs, enable the hot-add feature, and grow the environment as we progress. If I run into a ceiling then I may have to move to physical at some point, but probably not this year.

Thanks again!