Users Guide

Storage Solutions Guide 9
Passthrough Disk
A passthrough disk is a physical disk mapped directly to a VM (see Figure 3).
To the parent partition, the disk is an offline state and direct read/write access
to the disk is not available. I/O requests from the VM are passed through the
parent partition to the disk. With the parent partition free from managing the
disk, additional CPU cycles are provided for virtual machine processing.
When mapped to a passthrough disk, the guest OS has direct access to the
raw blocks of the physical storage device.
Figure 3. VMs Using Passthrough Disk
Considerations When Utilizing Passthrough Disks
• Hyper-V does not restrict multiple VMs from selecting the same
passthrough disk during VM configuration. If the same passthrough disk is
selected by multiple VMs, data may be inadvertently overwritten. Ensure
that you select the appropriate disk during configuration.