Users Guide

Storage Solutions Guide 15
• Windows Vista (x64) SP1
• Windows XP Professional (x86) SP2-SP3
• Windows XP Professional (x64) SP2
For a current list of guest operating systems that support synthetic SCSI
devices, refer to the Hyper-V Planning and Deployment Guide available at
www.microsoft.com/downloads.
Disk Interface Summary
Table 3. Disk Interface Summary
Understanding the Storage I/O Path
The storage I/O path is the path that a disk I/O request generated by an
application within a VM’s guest OS must take to a storage device. In general,
there are two distinct storage configurations based on the selected disk type
(VHD or passthrough), each with a unique storage I/O path.
VHD
The disk I/O request flows from the guest application through the storage
stack of the guest OS to the file system of the parent partition. The read or
write request is executed on the file containing the VHD, and then is routed
through the remainder of the storage stack onto the physical device.
IDE • All virtual machines must boot from an IDE device.
• A maximum of four IDE devices are available for each virtual machine.
• Virtual DVD drives can only be created as an IDE device.
SCSI • Preferred choice for all data volumes based on I/O performance.
• Requires that the guest OS has Integration Services installed.
• A maximum of four SCSI controllers are available for each virtual machine.
• Limit of 64 SCSI devices per SCSI controller.
• A subset of the Hyper-V supported operating systems support SCSI
devices.