Moving licenses around question

[Subversive]

Hi, I'm hoping this is possible.

We currently have 2 ESX hosts running. They're both Dual CPU Dell PE 2950's. The main resouce issue we have is RAM. CPU power is never an issue. I have access to another Poweredge 2950, single CPU though, and a PE 2850 as well. What I'd like to do is deploy ESX on both of them, and give each machine 1 CPU license. This will have a number of benefits. 1, if one of the hosts were to fail, a license could simply be given to one of the dual CPU boxes. It also allows me to have more memory in my cluster, and gives me much more flexibility when it comes to vmotioning stuff around. So, is it possible for me to leave each of the dual CPU hosts with licensing for only 1 CPU each and reassign the other 2 licenses to two more boxes? If so, how would I go about doing this? Thanks.

[Hairyman]

I don't believe it is possible to licence to a single CPU. I think VMware licences in pairs of CPUs. Plus you would have to make sure that the CPUs between the 9G servers and the 8G servers are compatible otherwise Vmotion will not work

- Aaron

[Subversive]

Yes, you're right. I should have checked before posting.

Thanks for the reply.

[Dave_Mishchenko]

You can license a single CPU (if that is what the host has) but you would have to purchase a dual CPU license. For your dual CPU hosts, they would still check out two CPU licenses. The other 2 host would only check out a single license. This has worked with ESX 3.0.x and is now supported with 3.5.

[Subversive]

So would it work to unlicense one of the 2950's completely, fire up the single CPU 2950, license it, then re-license the dual CPU 2950? It would only have 1 license to grab, theoretically?

Also, from my limited research, it looks like 2850 and 2950 are not vmotion compatible, based on this thread: http://communities.vmware.com/thread/55520 you need to do some tricky stuff to make it work, and I want this to be a proper cluster with HA and vmtion working properly.

[Dave_Mishchenko · Accepted solution]

It would fail because it would want to take 2 CPU licenses. You'd have to pull a CPU from the dual -cpu hosts to get all four running with just 4 CPU licenses. You could install ESX onto the extra 2950/2850 and leave them unlicensed. Obviously you wouldn't be able to run VMs on them, but you'd be able to use them as standby hosts.

Vmotion is based on the CPU type, so even in the 2950s you could have incompatabilities that would prevent vmotion unless you were to create a CPU mask. Here's a chart of vmotion compatability for Dell servers - . For a HA cluster, a VM is restarted from scratch so vmotion is not used. So in that case you wouldn't have to worry about CPU differences (well not unless you were mixing Linux and Intel/AMD processors).

[Subversive]

Okay, this makes excellent sense. Thanks a lot, and thanks for the CPU matrix, very handy!