Disk2VHD – a gem for practical migrations

A few people recently have remarked upon a handy little tool (all of 811KB) we use when we are helping businesses deliver IT migration projects. High time to trot out a quick blog entry then!

The tool is called Disk2VHD.exe, and can be downloaded free from Microsoft (link opens in new window).

You can run it from the command line or double-click to open its GUI.

disk2vhd screenshotIt’s easy to use – pick the drives you want to convert to VHDs, and set it going.

Two things however make it especially useful.

When you run it on Windows XP, you get the option to prepare the VHDs for use with virtual machines – which also means that you can mount the resulting VHD files as drives within Windows 7.

The second useful thing is that as the utility uses Volume Shadow Services, you can convert the disks of a running machine to VHDs “as you wait”.

This fits really well with our ethos of fast, practical processes that let you get on with the high value things. When our clients engage in XP->Windows 7 upgrade projects, a step we suggest they do, when migrating a machine, is to take a “safety copy” of the machines drives as VHD files onto an external 2TB USB drive. That way, even if the standard approaches to migrating user data and settings break, we have a copy of the old machine. If user remembers that they have 200 Internet Explorer favourites they forgot to migrate across, simply mount their old VHDs as drives, browse to the files they want in Windows Explorer, drag-and-drop the files and unmount the drive. In extremis, we can even start the old machine as a virtual machine. (You can use the Windows 7 boot loader to boot from a VHD).

Different clients keep the VHDs for different durations, from 2 or 3 days to “forever”. Obviously you need to make sure your physical security and processes are sufficient to protect the external drive if it has loads of machines’ VHDs on it…

Usually, you will end up with a VHD per drive, rather than per logical volume. Lastly, if you use disk-level passwords at boot time, be aware that you need to temporarily remove them when you create the VHD file. The largest VHD size supported is 127GB, and you should read the help and caveats on the page linked to above.

So there you go – a bit more technical than our normal blog posts, but too good a tool to ignore.