Shrinking a thick provisioned disk in VMWare ESXI 5.1

Being new to virtualization, I made the mistake of making the provisioned disk on my Windows 2008 template about 100 GB too large, resulting in our SAN being filled up too fast. Thinking that virtual machines were magical, and hardware could be configured as I wanted, I thought shrinking the disk should be easy. But it wasn’t. After going through a lot of guides, none that worked, I found this method to work:

Short version:
– Shrink disks in windows
– Do a V2V-conversion in VMware converter, with reconfig of the disk.

Longer version:

– Shrink the disk(s)/remove unused disks in the disk management tool in windows (a mmc snap-in in Windows S2008)
– Install VMware vCenter converter 5.0.1 (earlier versions like 5.0.0 isn’t compatible with ESXI 5.1)
– Choose “Convert machine”
– Connect to your vCenter administration machine as source
– Choose the machine you want to shrink the disk on.
– Connect to your vCenter administration machine as destination.
– Edit the disk-size (include only the drives you need) under options.
– Wait while copying
– Remove the old virtual machine (the source with too large disk)
– Profit!


Creating a windows server 2008 R2 template in vmware

This is mainly a short how-to for myself, after learning a few lessons.

  1. Create a virtual machine in VMware with a max 40 GB disk. It’s easy to increase the size of a disk in VMware, but a real pain in the ass to shrink a disk. All other hardware (CPU, RAM, network+++) is easy to reconfigure as needed.
  2. Install Windows Server 2008 R2 on the machine.
  3. Install all updates for windows via windows update.
  4. Run sysprep (with “generalize” marked) and power off the machine
  5. Use vSphere to create a template from the powered down machine.

Creating a template from a machine without sysprep just been run will create problems in your domain with IP conflict and name conflict, as you’ll have two machines with the same IP and Name. The machines SID will also be the same, so changing the name and IP on one machine will not make all the problems go away. I’ve learned this the hard way.