How to extend a boot or system volume on a Windows 2003 Server VMware Virtual Machine

You may have had a requirement to increase the space on the system drive of a Windows Server only to find that even though there is unallocated space to extend into you cannot extend the partition.

There is a neat workaround that I have tried a few times that works very well.

  • Power down the Virtual Machine
  • Make a backup copy of the Virtual Machine. Depending upon your flavour of VMware this can be done a number of ways. I like to browse the datastore using the VI client and take a full copy of the VM.
  • In the VI client edit the settings of the VM and increase the system partitions’ virtual hard disk to the desired setting and apply
  • Next you will need a second VM that is also running Windows 2003 Server. Power it down. In the VI client edit the settings of the second VM and Add a Hard Disk.
  • Select Use an existing virtual disk and Browse to the actual location of the first VM’s system disk
  • After you have added the disk and applied it, power up the second VM
  • Open Computer Management > Disk Management and you should see the system disk from the first VM with the accompanying Unallocated space
  • Run the Diskpart utility from Start > Run > Diskpart
  • Type list volume which displays all available volumes. Locate the volume to increase and type select volume x (where x is the volume number)
  • Finally type extend. If it has worked the message Diskpart successfully extended the volume should appear
  • Shutdown the second VM and in the VI client remove the hard disk from its configuration
  • Power on the first VM and voila, your system partition should now be fully utilising the allocated space