Changing from a Paravirtual to LSI SAS Controller (and visa-versa)

If you are in the situation where you have decided to use the paravirtual SCSI driver and then for some reason found out that you no longer wish to use it (for example if you are using Microsoft Clustering) - there is a way of getting Windows to boot correctly without throwing a BSOD.

This is a bit of a hack and slash method but (with my limited testing) appears to work OK for Windows Server 2012 R2. To get this too work firstly create an additional hard drive and attach it too SCSI port 1:0:0 (this will create an additional LSI SAS SCSI controller) and boot into Windows using the paravirtual SCSI controller. Once you have booted into Windows you should see "New Hardware Detected" - this is hopefully be installing the driver for the new (SAS) SCSI controller. Now if everything goes according to plan you should be able to shutdown your VM, change the paravirtual SCSI controller to SAS and successfully boot into Windows!