VMWare vCPU / Windows OS change question

I have a Windows 2008 R2 Enterprise Exchange server currently running 4 sockets and 1 core per socket. CPU usage hovers around 75-85% so I was going to add more power. I think I found that cores vs sockets were the same in VMWare so it doesn't make a difference if I go to 8 sockets and 1 core or keep the 4 sockets and up it to 2 cores per socket. I also saw where Enterprise will support 8 sockets.

The real question: is there a preferable way so that the Windows software doesn't balk at the change? I've seen articles saying that some OS's do not like changes to the CPU.

Second question: if I change it and Windows blows up, is it reversible just by backing the sockets back down to what they were? Would a snap before shutting the VM down and adding more CPU help in this case? Thanks
Mark LewisAsked:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Modern OS including Windows 2008, are plug and play, unlike earlier OS.

I would advise a FULL BACKUP of any VM before you make changes to any PRODUCTION SERVER.

Not a Snapshot.

So backup before a change.

I would recommend the use of Sockets, unless you have licensing restrictions, and need to use cores.

You are already running a Multi Processor HAL, so changes from 4 to 8, is just a config change.
It's always wise to take a snapshot before making changes. Andrew is right, though, a full backup would be even safer.

vCPUS in VMware can be grouped with multiple cores per socket in order to satisfy (or get around) software licenses that limit how many sockets (or cores per socket). There is certainly no requirement that the number of sockets or the number of cores per socket that VMware reports to the guest be the same as the actual installed hardware.

Since Enterprise supports up to 8 sockets, there's no effective difference between configuring it as 8 1-core sockets or 1 8-core socket or any of the combinations in between.

Windows Server should not need anything more than a reboot to recognize the changed vCPU configuration. If the VM was created with HotPlug enabled, you could add CPUs on the fly without a reboot; Windows 2008 supports it.

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