VMware ESX 3.5 and Disabling Cores

[RobBuxton]

Hi All,

We have a VMware ESX Cluster running ESX 3.5 U3 that has been built for a specific product that has a license model that doesn't fit well with the virtual server model.

The basis of this cluster is 3 x HP BL465c G1 Dual Core Servers with 16GB of Memory each. We're running out of memory and I cannot add memory without adding CPUs because of the AMD architecture.

Adding more CPUs will have a big impact on the license costs - again not VMware's licenses.

What I want to do is add a second DC CPU and then use the BIOS feature to disable half of the cores in each CPU. This will allow me to add an extra 16GB of memory per server and stay within the license constraints.

My question - has anyone disabled cores on a VMware ESX Host, specifically after ESX has been installed. Anything that needs to be done?

I tested the disabling cores feature on a Windows Server and that did replace drivers, just wondering if VMware ESX would need any similar updates / management.

TIA Rob.

[NTurnbull]

Hi Rob, adding an extra CPU to the ESX host shouldn't affect anything as the vm doesn't know anything about the amount of physical cpus or cores, the vm only knows how many virtual processors it has been assigned not what is physically in the host

Thanks,

Neil

[RobBuxton]

Neil,

Thanks - it's not so much the VMs, more about ESX itself.

In windows there's a difference between uni-processor and multi-processor HALs.

I don't think there will be the same issue in ESX, just trying to verify it.

[mcowger]

ESX doesn't care...bring it up with 1 CPU or 16 form the same install - doesn't matter (except the licensing, which obviously you've covered),

--Matt

[TomHowarth · Accepted solution]

you will be fine, other than the fact that by adding the second pCPU you will require an extra CPU license per host, ESX will not balk.

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Tom Howarth

VMware Communities User Moderator

Blog: www.planetvm.net