Provisioned Space Not Adding Up

[scotty_p]

I have a VM with a 275GB disk. I checked the directory of the VM and added them up and with the snapshots, deltas and everything else, it's about 280GB. However, when I check the Provisioned Space in vCenter it shows 552GB. How does it show this? Anyone know where this number comes from?

Thanks,

Scott

[golddiggie · Accepted solution]

2x drive storage (because of allocation for snapshots) + memory and overhead... So 275x2+RAM=~552GB

If you remove/delete the snapshots (these should be very temporary anyway) then your provisioned usage will drop to about 277GB

VMware VCP4

Consider awarding points for "helpful" and/or "correct" answers.

[scotty_p]

Interesting. Why does it show 2 x the disk size? Is that because of the snapshot? Thanks.

[golddiggie]

It is because of the snapshot(s) on the VM... With those, up to twice the amount of space provisioned for the VM is allocated (or the same amount of the vmdk provisioning) for snapshots/data retention. This is one of the reasons to not keep snapshots around for any length of time. Best practice is to keep them around for a few hours/days (at the most) to confirm that a configuration change hasn't had a negative effect and then you remove/delete the snapshot... Snapshots are also used by some of the B&R software so that you can continue to use/modify a VM while a backup is taking place. Once the backup is completed, the snapshot is removed and the amount of storage provisioned returns to normal.

How long have you had the snapshot(s) on the VM?? Remember, when you start the snapshot, it starts tracking EVERYTHING you do to the VM, both on the ESX/ESXi level and the VM's OS level, so it can quickly take up a good amount of space.

I would typically hold onto a major change item, such as updating the hardware version, for 1-24 hours, to ensure things are kosher before removing the snapshot. If using Update Manager, it has a built in snapshot retention setting that you can use (I would use the same time frame, or it's default for snapshot retention/time before delete)...

VMware VCP4

Consider awarding points for "helpful" and/or "correct" answers.

[RParker]

Interesting. Why does it show 2 x the disk size? Is that because of the snapshot? Thanks.

VM Ware uses some very ambiguous terms, and in plain english they don't translate well. Provision in this case is how much space you set aside for data. So you setup a VM to occupy 285 GB of space. Even though you may only use 40GB (for instance), it takes into account how much you can POSSIBLY use. So for snapshots, it is possible to use up ALL that space doubled, because snapshot (if every bit in the snapshot were changed) it is a copy of the original. Each subsequent snapshot therefore would potentially occupy the same space as the original, which is why it's so important to keep a close eye on snapshots.

So provision is space set aside for disk. Allocated is how much space is ACTUALLY being used. But in the real world you can use either interchangeable, and that's why the confusion. They should have said basic terms like USED and FREE, because after all it's just like disk data.

[scotty_p]

Thanks a lot for the explanation. I wasn't aware of that.