topic Disk Size Display Confusion in VMware PowerCLI Discussions

Disk Size Display Confusion

gamename — Mon, 30 Sep 2013 21:17:29 GMT

Hi,

I'm completely confused about what vSphere is showing vs what PowerCLI is telling me. To begin, PowerCLI shows what I expect for the disk size of a guest (~180G):

But, vCenter says I am using about 310G:

How can that be?

-T

Re: Disk Size Display Confusion

LucD — Mon, 30 Sep 2013 21:22:40 GMT

Are you by any chance using Thin provisioning ?

Re: Disk Size Display Confusion

a_p_ — Mon, 30 Sep 2013 21:24:24 GMT

That's certainly possible because the VM has an active snapshot, so the Used storage shows the sum of the base virtual disk plus the space used by the snapshot.

André

Re: Disk Size Display Confusion

gamename — Mon, 30 Sep 2013 21:33:44 GMT

Hi Luc,

Yes, it is thin. Is that a bad idea? Its certainly confusing.

(PS - Do you ever sleep?:))

Re: Disk Size Display Confusion

rtunisi — Tue, 01 Oct 2013 14:56:28 GMT

if you are using thin, there will be differences in provisionedSpace Size and usedSpace Size...on thick allocation, both will have the same values

When using snapsnots, the values will show the used size and plus the size of all disk deltas (as André said above)

about thin allocation:

not that this is a bad idea, the drawbacks on thin allocation lies at the more administrative overhead on your datastores. Some experts say thats a little bit of performance loss on thin allocation, which is a very discussable topic... you might want to find some articles about (try at Cormac Hogan blog. He's THE storage guy when the subject is virtualization).

and btw, dont think mr LucD Sleeps at all

Re: Disk Size Display Confusion

LucD — Tue, 01 Oct 2013 15:48:45 GMT

I do take an occasional nap :smileygrin:

I agree with rtunisi, Thin is not a bad idea, just remember that there are extra points to pay attention to.

Make sure to check the overcommitment and how much free space is left regularly.

But scheduling and distributing such a report is quite easy with PowerCLI.