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