Resizing Windows Server 2008 R2 virtual hard disk in VMWare ESXi

Posted on November 22, 2010 by


Top tip for those long in the tooth with virtual machines and needing to resize virtual hard disks.

This used to be difficult, and involve messing around shutting down servers and mounting the vmdk virtual hard disks as secondary drives on another server to perform the resize.

Now it is as easy as it could be, without even the need to shutdown the server (yes, even when resizing system partitions!). All you need to do is:

  1. Use the vSphere Client to edit the settings of the server and change the size of the hard disk(s) to the new size;
  2. On the server itself (RDP/console) run the Computer Management snap-in from the Administrative Tools menu;
  3. Expand Storage and select Disk Management. The drive you have increased in size will probably still be showing as the original size. This is because the virtual disk manager caches this information. On the right hand side, click More Actions and select Rescan;
  4. You should now see your new unallocated space. Right click on the *allocated* partition and select Expand.

Et voila! You have an expanded hard disk, in situ, without so much as a reboot required.

I hope this saves you as much time as it has me!