Today, we have experienced an issue with one of our Virtual Machine. It couldn’t boot up at all and gives us the following error when we are trying to power it on.

“Insufficient Disk Space On Datastore”

Looking at the VM’s settings, all of its Datastores are linked to a delta version with xxx-000001, xxx-000002, xxx-000003, etc…. This looks like a VMware Snapshots. From reading online, whenever you take a snapshot of a VM, it will saved all delta files (include the ones from different datastores) to the original datastore (which is usually the first one). What this mean is that if you didn’t allocate enough spaces on the original datastore and you are taking snapshots of the VM, it could run out of spaces because now all of your drives are inside the first datastore. This will give you the above error message.

This is by design and VMware site does have a solution, but it isn’t a full solution and require you to modify the VM’s .vmx file.

Creating snapshots in a different location than default virtual machine directory (link)

Cannot create new snapshots on a virtual machine after removing a disk from the virtual machine (link)