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Administering Windows Virtual Disks

  

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    Photo by teclasong

While reading my daily blog roll I ran across a posting at the always informative Train Signal Training blog about VHDs, or Virtual Hard Disks. This really caught my eye as I hadn't heard of this functionality before. Virtual disks have been a part OS X since the beginning (I believe they go back to the NeXT days) and I find them to be very useful. It's great to see this capability now in Windows 7 and Server 2008 R2. The steps to create and use a VHD are a bit more complicated than creating a DMG on the Mac, but that's a small price to pay for the capability.

As usual, I'm interested in the command line options and here Microsoft doesn't disappoint. The DiskPart.exe utility provides all the necessary functionality to create, partition, format, and use a virtual disk. Here's a session that creates a 32 GB disk and assigns it a drive letter.

PS C:\> diskpart
Microsoft DiskPart version 6.1.7600
Copyright (C) 1999-2008 Microsoft Corporation
On computer: AADEV
DISKPART> create vdisk file="c:\test.vhd" maximum=32000 type=expandable
  100 percent completed
DiskPart successfully created the virtual disk file.
DISKPART> select vdisk file="c:\test.vhd"
DiskPart successfully selected the virtual disk file.
DISKPART> attach vdisk
  100 perent completed
DiskPart successfully attached the virtual disk file.
DISKPART> create partition primary
DiskPart succeeded in creating the specified partition.
DISKPART> list partition
  Partition ###  Type              Size     Offset
  -------------  ----------------  -------  -------
* Partition 1    Primary             31 GB  1024 KB
DISKPART> select partition=1
Partition 1 is now the selected partition.
DISKPART> format quick fs=ntfs
  100 percent completed
DiskPart successfully formatted the volume
DISKPART> list volume
  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  ----  -----------  -------  ---------  ------
  Volume 0     D                      CD-ROM           0 B  No Media
  Volume 1         System Rese  NTFS  Partition     100 MB  Healthy    System
  Volume 2     C                NTFS  Partition     127 GB  Healthy    Boot
  Volume 3                      NTFS  Partition      31 GB  Healthy
DISKPART> select volume=3
Volume 3 is the selected volume.
DISKPART> assign letter=V
DiskPart successfully assigned the drive letter or mount point.
DISKPART> exit
Leaving DiskPart...
PS C:\> copy license.xml v:\
PS C:\> dir v:\
    Directory: v:\
Mode                LastWriteTime       Length  Name
----                -------------       ------  ----
-a---         9/08/2010   2:41 PM          418  license.xml

As you can see, it's pretty straightforward to create and use a VHD. You can even install Windows on a VHD and boot to it, which can be very useful for troubleshooting. I love finding a new features that I didn't know about and can explore.

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