Quite a few people out there make use of the excellent server virtualisation software produced by VMware so I thought I’d lay this tip out there for 64bit OSs.
It seems that VMware ESX 3.5 will not recognise your host server as being 64 bit compliant until you enable the right flags within the CPUs. In my case where I’m using a HP DL380 G5 which is 64 bit compliant then you have to enable Intel’s Virtual Threading (VT for short).
To do this, shutdown all of the hosted VMs and place the host into maintenance mode before shutting it down fully. Then boot back into the host BIOS (hit F9 after the HP splash screen). Once in the BIOS settings go down to “Advanced Options” and select Intel’s Virtual Technology / Threading. Exit out and here is the key point – you must full shut the server down.
This means all power cables out and left for a good 60 seconds at least! Miss this step out and you won’t get anywhere fast.
Once VT has been enabled spool the VM back up and create 64 bit virtual machines to your hearts content.
Extra tips:
- I’ve heard that any VM created prior to this change will not register the change in CPU so will have to be created again.
- Paravirtualisation should also be turned off. Whilst this should only affect the *nix kernels there have been reports of it messing with Windows OSs if set prior to initial build.
- Anything prior to a G5 will most likely not be x64 compatible so no dice.
Ramblings From The Litter Tray of Life 