Thursday 18 March 2010

Tool To Create Fixed VHD Files _Fast_ – VHD Tool

This tool is awesome!

Creating a fixed size VHD in Hyper-V Manager can be a painfully slow process as it creates the disk. The larger the VHD, the more painful things get.

The following tool eliminates that:

We downloaded the tool and copied it onto the local workstation. We then ran through and created a 10GB fixed VHD using the tool. The creation process was virtually instantaneous!

The creation process:


  • vhdtool /create TestVHD.VHD 10737418240
    • Creates a 10GB fixed size VHD file.

We then opened the created VHD via Windows 7 Disk Management console, formatted it and ended up with:


Note that the file size needs to be in bytes. So, here is a handy converter:

Philip Elder
Microsoft Small Business Specialists
Co-Author: SBS 2008 Blueprint Book

*Our original iMac was stolen (previous blog post). We now have a new MacBook Pro courtesy of Vlad Mazek, owner of OWN.

Windows Live Writer

1 comment:

stryqx said...

Hi Phil,

The reason VHD Tool is so quick is that it doesn't zero out the allocated space, unlike the Hyper-V Manager.
This means that you can lift the existing data off the physical disk inside the VM using something like a disk sector editor, or memory-mapped I/O. This can even be done if the VHD is quick-formatted.
So you need to consider when to use VHD Tool and when to use Hyper-V Manager. On a new system it's fine; on an existing system you should weigh up the risk of potential data leakage before using VHD Tool.