Hyper-V Increasing hard drive size

Posted on 2011-04-20
Last Modified: 2012-05-11

I am running windows server 2003 as a virtual machine (Hyper-V). I have reached capacity (30gb) on my allocated disk space (on the virtual machine)

I have stopped the virtual server in Hyper-V, right clicked and used the expand option to double the drive capacity (now shows as 60gb). After restarting the server and going into disk management, I now have my c drive and 30gb of unallocated space.

I have tried using the DISKPART command to extend the partition (extend size=2000) but I keep getting the message "The volume you have selected may not be extended. Please select another volume and try again"

Is there any way to get round this, any tool i can use (preferably free) which will simply merge to the two partitions and not affect anything in the process?

Thank You, looking forward to finding a solution!
Question by:Antikythera
    LVL 116

    Accepted Solution

    1. Power Off the Server,
    2. Download the following iso cdrom from

    3. Mount the iso cdrom in the virtual machine.

    4. Wait for the cdrom to boot.

    5. Expand the partition.

    (see instructions if not clear

    6. Shutdown and restart VM.

    7. Done.

    8. Please ensure you have a valid backup before altering partitions.

    LVL 116

    Expert Comment

    by:Andrew Hancock (VMware vExpert / EE MVE)
    Another method for your consideration.

    You cannot use diskpart to extend the system partition (C: drive).

    But you can attach this 60GB C:\ to another Virtual Machine, boot that virtual machine with this disk attached, and Extend the parition in that Virtual Machine.

    i.e. extend the D:\ drive or Disk 1 (2) of that machine.

    Shutdown, detach, and reboot original machine, and it will be extended.
    LVL 13

    Expert Comment

    by:Greg Hejl
    hancock has it right

    also make sure you compact and make the drive fixed

    make sure you are using data disks for server data (don't store anything but OS on C:\ vhd)

    Author Comment

    Hi Hancocka,

    If i use the second solution, what is the process to dettach the drive from the virtual machine and to then attach is as a secondary drive to a secondary virtual machine?

    Once it is attached do i then simply use the diskpart command to extend the partition?

    Thank You
    LVL 13

    Expert Comment

    by:Greg Hejl
    you can use extend volume in disk management
    LVL 116

    Expert Comment

    by:Andrew Hancock (VMware vExpert / EE MVE)
    yes, use the same function as before. diskpart.

    Author Closing Comment


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