Multiple CPUs on XP Guest OS

[dareames]

I'm relatively new to ESX. I'm trying to create an XP virtual machine with 2 CPUs. The ESX server has 2 CPUs and I already have a couple of server guest OS's that have multiple CPUs, but it won't let me have more than 1 CPU for XP Professional. Is that by design or am I missing something? We also have several VMWare Server machines (free version) and I've created an XP virtual machine on those with 2 CPUs. Why won't it let me on ESX? I'm using ESX 3.0.0. Thanks in advance for any help!

Doug

[TCronin]

Multiple CPU's for XP is not supported on ESX 3.0.0, it was introduced in ESX 3.0.1. The latest version available is ESX 3.0.2.

Be careful with mulitple CPU's in guests. The guest OS has to schedule on all it's CPU's at the same time. If you only have 2 CPU's in your host then you will always have Readytime accumulating (time where the guest is ready to use a CPU, but one is not available on the host), even if only one guest is running becuase at a minimum you have the Service Console also running.

The more guests you add with multiple cpus, the worse it will get. And in 99.9% of the cases their is no advantage to having the second CPU. Out of over 1200 guest running in production I have only 5 dual CPU guests. 2 of those actually improved performance with the second CPU, the other 3 are still dual cpu due to political reasons, not technical. I've also solved a couple dozen performance issues buy removing the second CPU.

[dareames]

Thanks for the quick reply!!! I was hoping there might be an upgrade that would fix it. I actually meant to say that the current guests have the "option" of multiple CPUs. I went to edit them and there was an option for 1, 2 and 4 (because of hyperthreading). I didn't actually change them, just checked to see if it was an option. The guest I'm trying to put 2 CPUs on has a problem with the application that's running on it. Another user of this application that is running it on a virtual machine said he had the same error until he added a second CPU. The current production box for this application is a Dell OptiPlex tower in one of our server racks running 2000 professional and I really need to get that machine out of the server room. Looks like I'll be scheduling an upgrade of my ESX server. Thanks again for the help!!

Doug