tkutil,

Depends on the operating system installed in the template. From the command line of one of your ESX hosts you can use vmkfstools to expand the VMDK:

vmkfstools -X50G mynewmachine.vmdk

will expand your VMDK to 50GB. That will only expand the underlying virtual disk - not the filesystem on the virtual disk.

For Windows VMs we use Windows PE as a loading mechanism and we can PXE boot the VM and use diskpart to extend the filesystem even on the system partition (i.e. the C:\ drive) of a Windows VM. One could also use BartPE I would assume.

Here's our process to extend to 50GB for a Windows-based OS:

. Deploy new VM from template

. vmkfstools -X50G newmachine.vmdk

. Boot to WinPE and get to a command prompt

. Run diskpart and run the following commands at the diskpart> prompt

. select disk 0

. select partition 1

. extend

For Linux, it would depend on the distro. On RedHat/Fedora-based distros with the root filesystem on a Linux LVM logical volume the process would be basically the same first 2 steps above then:

. Create a new physical partition with fdisk

. Change the partition type to Linux LVM (partition type 8e)

. Boot into Linux

. pvcreate on new partition

. vgextend onto new physical partition

. lvextend current logical volume

. resize2fs the current filesystem on the logical volume to the new size.

I leave other OSs as an exercise for the reader

Hope this helps.

EDIT: you have to boot to PE or some other offline OS to extend the system partition on Windows because you're not supposed to be able to extend the system partition.