Comments on: How large can virtual machine snapshots grow?

By: Esiebert7625

Esiebert7625 — Wed, 27 May 2009 20:33:07 +0000

You say “snaps” as stated in the post multiple snapshots can grow larger than the original disk size but a single snapshot can never grow larger than the original disk size:

“Now this only applies to a single snapshot. It is possible for the combined disk space total of multiple snapshots to exceed the size of the original disk file. ”

What are your disk sizes/snapshot sizes and how many snapshots do you have?

By: WkdPanda

WkdPanda — Wed, 27 May 2009 20:14:28 +0000

Ok, you guys need to do some more testing.

I have a Win2k3/Exch03 server that was snapped in Nov 08. ESX lost track of the snaps, so they are still there, but not seen. Right now, [B]I have 500Gb of disks, and 650Gb of snaps[/B]! Yes, larger than the original, and yes, I have had VMware support (those wonderful guys in IRE) on the phone while looking at it. It takes 2.5 hours to cold boot the system, because of the snaps.

By: Esiebert7625

Esiebert7625 — Wed, 17 Dec 2008 22:17:31 +0000

It can potentially be 10GB if every single block of data is changed on the disk after the snapshot is taken. Snapshots only grow when data is changed on the original vmdk file after the snapshot is taken. It’s more about which data changes on the disk rather then how much data is changed. For example if the same 1GB block of data is changed over and over and nothing else is changed then the snapshot will only be 1GB in size. If 5Gb of data is changed one time then the snapshot will be 5GB in size but if that data is changed again and resides on those same disk blocks then the snapshot will still only be 5GB. Hope that helps.

By: Nickmanderson

Nickmanderson — Wed, 17 Dec 2008 22:04:45 +0000

Quick question. Say I have a 10gb .vmdk file with 9gb being used. Now say I create a snapshot…so, can this snapshot get to be 10gb or will it only grow to 1gb? Any help with this is much appreciated. Thanks.