In
fact, increasing the size of a VMware Virtual Machine Disk (VMDK) is
straightforward, and is supported in the vSphere Client, by selecting the
virtual hard disk, and increasing the size using the up arrow. or typing in a
new value.
However,
you cannot shrink the disk in this way, it’s not supported. The only supported
method of shrinking a VMware virtual machine disk (VMDK) is to use VMware
vCenter Converter Standalone and create a virtual to virtual (V2V)
conversion,
a similar process to a Physical to Virtual (P2V) conversion.
The
following procedure should be followed to shrink the VMware VM Disk:
1.
RDP to the VM for which the disk size
is to be reduced.
2.
Select Disk Management, and select
the partition you need to shrink.
3.
Right Click the Volume/Partition to
shrink, and select Shrink.
4.
Enter a size to reduce the OS
partition.
5.
In this example the VMware virtual
machine disk (VMDK) is 30GB, and we would like to reduce the size of the VMware
virtual machine disk (VMDK) to 20GB.
6.
Enter the figure 20 (GB) x 1024 =
20480
7.
Now you can see an unallocated 20 GB
space on the virtual disk
8.
Power OFF the Virtual Machine, and
navigate to the datastore path where the VMware virtual machine disk (VMDK) is
located using Putty
9.
We need to edit the *.vmdk, which is
the descriptor file, which contains the variables for the size of the
*.-flat.vmdk.
10. The number mentioned under the heading #Extent
description, after the letters RW, defines the size of the VMware virtual disk (VMDK).
11. We wanted to reduce the size of the VMware virtual machine
disk (VMDK) from 40 GB to 20 GB. So the value we need to enter into the
descriptor file is:-
20 GB = 20 * 1024 * 1024 * 1024 / 512
= 41943040
12.
Using vi, edit the descriptor file,
and change the number from 125829120 to 41943040, and save the file.
125829120 is calculated from 80 GB =
80 * 1024 * 1024 * 1024 / 512 = 125829120
13.
Migrate or Copy the virtual machine
to another datastore.
14.
After the virtual machine disk (VMDK)
has been moved, you will notice the disk size reflects the desired size of
20GB.
15.
After restarting the virtual machine,
and checking with Disk Management, you will notice the 20 GB unallocated
storage space, has been removed, and disappeared.
