I have seen blog posts saying that there is no support for SCSI in Hyper-V. That’s not exactly true :). Microsoft said that you can use SCSI controllers for disks but not for your boot disk, the Boot disk must be on an IDE controller. But before making decision not to use SCSI controller, you should know that Hyper-V uses an emulated IDE controller. This means there is a little bit of overhead in processing disk operations.
For SCSI support, Hyper-V uses a SCSI controller that is not emulated. Instead it uses the virtual machine bus which is much faster and requires less CPU overhead.
As you probably know, the best practice is to separate your Data from your Operating System (OS). I always install the operating system is on C: and store the data on D: drive. In Hyper-V environment, C: will be a virtual disk on the IDE controller. D: should be a virtual disk on a SCSI controller. Just test this and you will see that it’s a not so bad idea ;).