Virtualizing a Windows 2000 host for use in Hyper-V

Both of the other answers are correct. Calling Microsoft for support with Hyper-V and Windows 2000 will result in being told that the only supported configuration involves one virtual CPU.

With that said, I suspect that you got exactly the same performance each time because Windows 2000 didn't automatically reconfigure itself as a multi-processor installation when you added virtual CPUs. Win2K was only using one CPU, even when you assigned it four.

You need to go to device manager and change the HAL from the single processor HAL to the multi-processor HAL. (Update driver on computer type.) That will trigger the installation of the multi-processor kernel, ntdll, HAL, etc. My memory says that there were about six binaries that changed.

Note that this is a one-way trip. Your Win2K VHD will be running multi-processor code indefinitely after that, even if you go back to a single virtual CPU. You might want to back up your VHD first, as these multi-processor binaries are less efficient than the single-processor ones when running single vCPU.

Lastly, please understand that the reason that Microsoft isn't supporting more CPUs for Win2K has partly to do with the fact that the Win2K kernel has no idea isn't being virtualized and it has some hard assumptions that all CPUs run all the time. Breaking this assumption by virtualizing more processors will result in less than linear performance gains (cough, cough.) You might get reasonable performance with two processors. More will probably not help.

The problem is the way the pass-thru disk was configured. If you add the disk to the cluster resource that represents the guest manually, the host server will mount the volumes on the disk before bringing the guest online. This renders the disk unavailable inside the guest.

You can verify that you have this problem by looking at "Services and Applications" in the Failover Cluster Manager. Looks at the VM guest and find the list of "Disk Drives". If the "File System" is listed as NTFS, then the host has the volume open. If the "File System" is <unknown> then the volume is already configured correctly.

The correct sequence for adding a pass-thru disk to a highly available VM (i.e., guest running on a clustered Hyper-V host) is a follows:

1. Present the storage to the cluster. (Configure the iSCSI session, etc.)
2. Open Disk Management.
   • If this is a blank disk, right-click the disk and pick Initialize. Right-click again and take it Offline.
   • If this disk already has data on it that you want to preserve, right-click the disk and bring it Online, then right-click again and take it Offline.
3. Open the Failover Cluster Manager and navigate to Storage.
4. Click "Add a Disk" and select the disk.
5. Right-click the disk and pick Properties. Name the disk something useful. Also note the disk name above the volume list. You'll need this name later. (In this example, the disk is named Disk5.)
6. Go to "Services and Applications" in the Failover Cluster Manager console and find your VM. Alternatively, open the Hyper-V management console.
7. Right-click the VM and pick Settings.
8. If the VM doesn't already have one, add a SCSI controller.
9. Add a new disk to the SCSI controller. Select the "Physical hard disk" option. Choose the disk name your found in step 5. Click OK.
10. Complete the disk configuration inside your guest.

If you already have a volume configured incorrectly and you want to fix it:

1. Shut down the guest.
2. Remove the pass-thru disk from the VM configuration.
3. Remove the disk resource from the VM in the "Services and Applications" screen of the Failover Cluster Manager console.
4. Open the VM configuration and add the pass-thru disk back. (See steps 5-10 above.)