Used Storage versus Provisioned Storage

[jasonvines]

I have two ESXi 4 hosts setup and all of the hosts show the provisioned storage much higher than the what I actually configured them for which shows as used storage. Some of them are almost double their original size. What causes this? I migrated a few of the virtual machines but haven't done much beyond that. Anyone have any ideas? This one below I actually created it as 40GB and have not migrated it or done anything other than install a small applicationand take a snapshot.

[jasonvines]

Actually I just found part of my answer. It is snapshots that's increasing the usage above the 40GB I set, however I don't see anything that is cause me to to be provisioned for 88 GB.

[MKguy · Accepted solution]

That is because with a snapshot, you actually do provision the double amount of disk space to the VM. The snapshot delta file can grow to the same size of the original hard disk (in the worst case if the VM is very IO-active and you don't remove snapshots soon). Also, ESX uses a swap file for each VM with the size of the RAM allocated to the VM (if you don't use reservations), in case physical RAM becomes scarce (memory overcommitment).

The value displayed as ``provisioned'' is correct. Whether you size and expand your storage for what you provision (to protect of a worst case) or what you actually expect to be ``used'' is up to you.

[J1mbo]

It's as though snapshots are thin provisioned to the maximum size.

Please award points to any useful answer.

[jasonvines]

Okay that makes sense. I was starting to come to that conclusion, but just wasn't quite adding up in my mind.

Thanks

Jason