Extending a vSphere Win2K3 OS drive

by Mike · 6 comments

in Tips and Tricks,vSphere

We’re in the middle of a VMware migration from 3.5 to 4.  Some of the older VMs have small C drives, and since Microsoft loves to release tons of patches, they’re running out of space.

In the past you could shut the VM off, attach the OS drive as an extra HD to another VM, increase the space and then use diskpart to extend it.  With VM Hardware v.7, it’s much easier!

Grab the ExtPart tool from Dell here.

1) Edit the VM’s settings to increase the disk size

2) Copy ExtPart to the VM and double-click to extract.  Default path is C:\Dell\ExtPart\

3) Check the Partitions before:

4) From a command-prompt, change to the ExtPart directory

5) Run extpart.exe

6) Enter in the disk you want to extend in lower-case, i.e., c:

7) Specify in MB of the amount of space you want to ADD, not the final total

8) Check partitions after

9) That’s all!

*note:  your partition in “Disk Management” will look funny until you quit and re-open Disk Managment:

{ 2 trackbacks }

VMware – Extend a vSphere Win2k3 C Drive «
August 13, 2010 at 3:22 pm
Expand C: drives on servers |
January 16, 2015 at 1:43 am

{ 4 comments… read them below or add one }

1 Jaime Luciano October 15, 2010 at 8:50 am

First of all, thank you for the step by step instruction they were very helpful. Sometimes is hard to remember small details that are very useful, I just want to add that in order to extend the VM disk size it’s necessary to have the virtual hdd in dynamic type.


2 Rich Chodacki January 7, 2011 at 9:59 am

Thank you for this tip, worked for me without a hitch: vSphere 4.1.0 260247 for guest running Windows 2003 R2 32-bit.
Also, to get the exact size to increase the disk, its quick to just get properties on the new volume from within disk manager, select the Volume tab. This lists the available size in mb.

3 Maximo January 22, 2014 at 7:49 pm

“Extend vSphere Win2K3 VM OS Drive – No Reboot Needed!
:: The vLab” was in fact a great article and I really was indeed extremely content to discover
the article. Thank you-Alica

4 Rae August 19, 2017 at 2:27 pm


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