We know that Hyper-V virtual machines require booting from virtual IDE. Historically, in the physical world, SCSI can provide better performance than IDE. Does that mean we’re giving up performance booting from virtual IDE?
On the surface you’d think that is the case as the I/O performance of physical SCSI and IDE devices can differ significantly. In a Hyper-V environment this is not true for the virtualized IDE and SCSI devices. In Hyper-V IDE and SCSI devices both offer equally fast I/O performance when integration services are installed in the guest operating system, so requiring to boot from a virtual IDE vs. a virtual SCSI drive does not affect the boot performance of the virtual machine.