Create a linked clone in Vmware's Vsphere to save disk space

How to create a linked clone in Vsphere:

Are you trying to grow you lab two-fold? Or a hundred-fold? Before you know it, your 1TB drive looks infant-like and you're screaming at Microsoft for taking up too much space for their OS.

Well, it appears we are in luck courtesy of Vmware's 'linked-cloning' option. Here's what I found courtesy of sanbarrow.com:

This is what you need:

Only tools used are the vSphere client and a text editor on a Windows host.

First create the master VM.
It is recommended to use a thin disk ...

Give it a reasonable name - so that it stands out from the other VMs.
In the example I called the VM "dont_touch"



Install the new VM and when done reboot it and install VMware-tools.
Feel free to add more apps ... or sysprep the master VM ...
Once you are satisfied power down the VM.
Now create a snapshot with the vClient.
See the screenshot - the files that belong to the snapshot are hilighted.
From now on regard the directory "dont_touch" as readonly. Do not start the VM again.




Next use the datastorebrowser and download the two files hilighted in the next screen : the vmx and the snapshot-vmdk.



On your Windows-host the two downloaded files should now look like this.
Don't worry - the datastorebrowser is a funny guy - he shows you two files but downloads three.
And ... he thinks this is helpful ;-)





First thing to do is edit the "dont_touch-000001.vmdk"
It now looks like :

---

# Disk DescriptorFile
version=1
encoding="UTF-8"
CID=fa3d08b7
parentCID=fa3d08b7
createType="vmfsSparse"
parentFileNameHint="dont_touch.vmdk"
# Extent description
RW 25165824 VMFSSPARSE "dont_touch-000001-delta.vmdk"

# The Disk Data Base
#DDB
ddb.longContentID = "9b8da3d63cda1e5dbea7c0f4fa3d08b7"

---

As we want an absolute path for the parentFileNameHint parameter we edit the vmdk-descriptor so that it looks like:
Note the yellow line ! It shows the edited path.

---

# Disk DescriptorFile
version=1
encoding="UTF-8"
CID=fa3d08b7
parentCID=fa3d08b7
createType="vmfsSparse"
parentFileNameHint="/vmfs/volumes/4ba3aca0-eca4fd60-312d-f4ce46af50b6/dont_touch/dont_touch.vmdk"
# Extent description
RW 25165824 VMFSSPARSE "dont_touch-000001-delta.vmdk"

# The Disk Data Base
#DDB
ddb.longContentID = "9b8da3d63cda1e5dbea7c0f4fa3d08b7"

---

Tip: to find out the absolut path look it up in the vmx-file - the parameter sched.swap.derivedName
also uses the absolut path.

sched.swap.derivedName = "/vmfs/volumes/4ba3aca0-eca4fd60-312d-f4ce46af50b6/dont_touch/dont_touch-aafe8f9c.vswp"

The part marked in yellow shows the absolute path that is required to adjust the vmdk-description.
Now is also a good time to delete that parameter from the vmx-file. Don't forget that !

Now we can create several copies of the vmx-file.
Give every file a new name and adjust the display name parameter.

displayName = "2k3-clone-1"

Screenshot below shows several new copies of the vmx-file - each one has the display-name adjusted and the
sched.swap.derivedName line removed.



Now back on the ESXi create several new directories for the clones.



Into each new directory copy the appropriate vmx-file plus the two vmdks.
Again - don't worry - you need to upload three files but datastorebrowser only displays two.



Now all is left to do is add the vmx-file to the inventory and make sure you click "I copied it" on first launch.




During first boot of the cloned VM it is advisable to unconnect the network-card.
On a Windows VM you may want to run newsid.exe, change the hostname and configure the network on first boot.
Then reboot and enable the nics.


This is of great value for expanding a Virtual 'lab' environment while minimizing disk space.
Quick note:  You can have up to eight virtual machines in a linked virtual machine group. So there is a maximum number of linked clones per 'master' VM.

*Note: Not my original work...This was taken directly from http://sanbarrow.com/linkedcloneswithesxi.html

Thank you for sanbarrow for this awesome tutorial!