The following table shows changes in storage. Some of the changes are performance related like hot add of storage. This helps performance by reducing the time it takes to add new storage. The big things to note are increases in IO Sizes passed from VM’s and huge improvements in Dynamic VHDs.
Virtualization Feature
WS08 + RTM Hyper-V
WS08 SP2 Hyper-V
Windows Server 2008 R2 Hyper-V
Dynamic VHD Performance
Writes 3x slower than fixed. This is due to limited meta data caching.
Dynamic and Fixed Disk performance at almost parity
Diff Disk Scaling Performance
1x
4x – 5x
IO Sizes (Virtual SCSI)
64KB
8MBytes
(improves throughput)
IO Size (Virtual IDE – no changes just for comparison)
VHD Block Size
512KB
2MB
Fixed VHD Creation Speed
3x – 4x
Hot add of storage
No
Yes
SCSI Command Pass-through
** Fixed Disk is highly recommended for Production