Users Guide

32 Storage Solutions Guide
Sizing for VHDs
Each LUN should be sized to support the target VHD. If the VM files will be
stored on the LUN, then that must be taken into account as well. To avoid
warning messages generated by the parent partition concerning disk running
out of capacity, the LUN should have an addition 200MB allocated and this
should be left as empty space on the volume.
NOTE: For increased performance, fixed disk VHDs are recommended. It is also
recommended that each VHD be placed on its own LUN (see Figure 14).
Figure 14. VHDs With Dedicated LUNs.
VM checkpoints (referred to as snapshots in Hyper-V Manager) reduce I/O
performance and are therefore not recommended for production
environments. If checkpoints are utilized, additional space requirements for
the checkpoints must be taken into consideration. All checkpoint files,
including the differencing disks and virtual machine state files (memory and
configuration), are stored in a directory available to the parent partition. By
default, the directory is on the same partition as the boot VHD. When a