Resizing Windows Volumes / Drives in VMware vSphere / ESX

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This article is primarily geared towards making your guest virtual machines hard drives LARGER, If you want to SHRINK or make the drive smaller then see the following article.

Resizing Guest Hard Drives using the VMware Converter


Re sizing a Guests Hard Drive (Make it larger)

1. On the properties of the VM select the hard disk in question and locate its size.

locate hdd sze

2. Enter the new size and hit OK. Note: Making the drive size smaller, will have no affect, if you want to do that clone the drive. If the option is “Greyed out” then make sure you DO NOT have any snapshots for this machine.

change hdd size for vm

Re-sizing the guests “Volume” Option 1 – Graphically

Note: To do this using diskpart skip forward to number 10.

3. On the guest > Right click “My Computer” > Manage > Locate “Disk Management”. You will see there’s some free space that’s appeared on the end of the drive, (Click action > Re-scan if you can’t see it).

locate free space

4. Simply right click the existing volume and select “Extend Volume”.

how to extend volume grpahically

5. Next.

extend volume

6. Copy in the extra space you want to assign (all of it probably) > Next.

extend volume wizard

7. Finish.

8. All the physical drive should now be committed.

commit changes to drive

9. And just to be sure, look in “My Computer” the drive is now 300 GB.

drive size

Re-sizing the guests “Volume” Option 2 – From Command Line with diskpart

10. Start > run > cmd{enter}

diskpart list volume&lt select volume x –Where x is the volume number of the volume to be re sized

skpart list volumedi

11. The final command is simply extend (This uses ALL the available free space.) Note the volume size in the picture below has jumped up by 40 GB.

diskpart using exend

Resizing a System (boot) Partition.

Server 2008 R2 and Windows 7 can do this quite happily. Older versions of Windows do not like having their system drive re sized, you see the following error if you try,

Error: The volume you have selected may not be extended. Please select another volume and try again.

The volume you have selected may not be extended.

Option 1 (Connect this drive to another machine)

In a virtual environment this is much simpler, but even if its a real physical hard drive, you can put it into another server and re size it. In an ESX environment simply do the following,

1. Shut down the machine that needs its drive re sizing, then go to another virtual machine’s properties and select add.

add hard drive to vmware

2. Hard Disk > Next.

3. Select “Use existing virtual disk” > Next.

use existing virtual disk

4. Browse to the the drive we want to re size > Next.

vmdk location

5. Next.

scsi options vm

6. Finish.

add hard drive to virtual machine

7. Now on the VM (Action > Re-scan disks). You will see the drive, and it’s not listed as a system drive, so you can extend it using any of the methods listed above.

use free space with diskpart

8. For example, heres the drive re sized using disport.

diskpart extend

9. when you have re sized the drive go back to the properties of the machine you have connected it to, and remove it.

remove vmdk

10. OK.

remove disk form vm

11. Now power on the original VM and drive will be re sized.

resize vm disk

Option 2 (Re size the Windows volume with GParted)

Note: This will work for a physical server as well.

1. Here’s our system drive with some nice shiny free space.

repartition servers c drive


2. Make sure the server in question can boot from CD, in VMware do the following to boot to the machines BIOS, for a real server watch the screen as the server boots for instructions (Usually F10, F1 or Esc but differs depending on vendor).

boot vm to bios

3. Locate the boot order and make sure CD/DVD is at the top of the list.

bios boot order vmaware

4. Download GParted burn the image to CD, if you are working on a real server (use ImgBurn if your stuck). Or simply point the VM to the iso image, and boot the machine in question from it. At the welcome screen press Enter.

linux partition editor

5. Use your arrow and tab keys to select Don’t touch the keymap > OK.


6. Pick a language.

language selctionn linux

7. We want to launch the GUI (X Windows), so select 0 (Zero).

boot to linux

8. Select Re size/Move > Drag the arrow to include the free space > Re size/Move.

change c drive size

9. Apply

repartition vm

10. Apply.

apply partition changes

11. Close.

change partitions with boot disk

12. Click GParted > Quit.

gparted with vmware

13. Exit > Reboot/Shutdown > OK.


14. Remove the CD/ISO and press Enter.

repartition vm with boot disk

15. The guest will run chkdsk the firs time it boots. This is normal don’t panic.

chkdsk running

16. Once booted the volume will be re sized.

resize boot partition

Shrink a Windows Partition with diskpart

1. To actually make the volume smaller with diskpart, the initial commands are the same.

vmware diskpart

2. If you use “shrink” on its own is will shrink the drive as much as it can (I cannot think of any situation where you would do this!). So to shrink the volume by 10 GB simply issue a “shrink minimum 10240”. (The figure in in MB).

diskpart shrink


Related Articles, References, Credits, or External Links

Original Article Written 24/01/11

Author: Migrated

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