Once in a while you have to change the size of a VHD file and I think I have found the perfect tool for the job. It is called VHD Resizer (previously known as VHD Expander) and it very easy to use. You can grab it from the vmToolKit (http://vmtoolkit.com/) website and expand or shrink the size of any Virtual Hard Disk file with just a few clicks.
Once you start the program you have to select a VHD file to work with and choose how to change the original VHD file.
You can choose the type of the VHD file (Dynamic or Fixed) and also the new size of the disk in GB or MB units. Click resize and after a couple of minutes, depending on the size of the disk files, you will have the resized file.
Mount the new file onto your Virtual Machine and you are almost ready to go. If you have expanded your VHD file, most probably, the partition that your Virtual Machine uses is not the correct size and the newly added space is reported as unallocated.
Use your favorite partition management tool, expand the partition, and you are ready to go.
Of course, you could do the geeky thing and use DiskPart utility to change the size of a VHD file. There is lengthy description of this utility called “A Description of the Diskpart Command-Line Utility” that you can find here .