Change cpu number for virtual machine

Hi Experts,

I want to increase cpu number in ESX1 4.1 for one of its' guest OS.  I got a warning that “ Changing the number of virtual processors after the guest OS is installed may make your virtual machine unstable” .   The guest OS is W2003.

So I am wondering if I can do it or not.  Please advise.

Thank you so much.

EN
EnjoyNetAsked:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
This is just a warning it will not affect the VM.

However, you may have to change the HAL, to enable multiple CPUs in Windows 2003.

Select Device Manager, and change the Processor to a Multiprocessor, after you have made the VM change.
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andyalderCommented:
The warning is there because the guest needs different drivers to deal with multiple CPUs than with single ones and VMware can't make those changes because it has no access to the internals of Windows or Linux kernel. With Windows you have to change to multi-processor HAL. You also have to make sure you don't give it more vCPUs than the OS can handle. Whether you get better performance with more vCPUs is down to the scheduler, it can slow it down rather than speed it up if VMware has to hold the guest while waiting for the required number of vCPUs are available.

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003978 applies,
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