Reduce CPU's on a Guest

[Ekoesling]

If I decrease the number of CPU's on a guest (windows 2k or 2k3) will I run into problems?

[Viperman]

No,

In fact in Windows 2000 it isn't a terrible idea to build the guest first with multiple CPU's so that it will have the multiple CPU HAL.  Then if you bring it down to single CPU it will still perform fine.  In 2003 it doesn't matter going forward and backwards that HAL is pretty resilient.

Funny thing about going to a single CPU is that it will probably actually perform better with 1 then with more than 1.  You need to monitor it and then adjust as needed.  Had one student whose server had 4 vCPUs and it was running at 96% utilization, which seems like it need MORE CPU.  He decreased it to a single CPU and it went to 6% utilization and performed wonderfully.

[Ekoesling]

Very good, I thought I had remembered that.

Now, can this be done without rebooting the box?