Storage improvements from Windows Server 2008 SP1 Hyper-V to Windows Server 2008 R2 Hyper-V
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. |
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 |
1x |
4x – 5x |
IO Sizes (Virtual SCSI) |
64KB |
64KB |
8MBytes (improves throughput) |
IO Size (Virtual IDE – no changes just for comparison) |
64KB |
64KB |
64KB |
VHD Block Size |
512KB |
512KB |
2MB |
Fixed VHD Creation Speed |
1x |
1x |
3x – 4x |
Hot add of storage |
No |
No |
Yes |
SCSI Command Pass-through |
No |
No |
Yes |
** Fixed Disk is highly recommended for Production