Try "aggr show_space"
----- Original Message -----
From: Stephen C. Losen <scl@sasha.acc.virginia.edu>
To: Borzenkov, Andrey <Andrey.Borzenkov@fujitsu-siemens.com>
Cc: toasters@mathworks.com <toasters@mathworks.com>
Sent: Thu May 22 07:29:53 2008
Subject: Re: "df -h" shows less snapshots than "snap delta"
> I am rather puzzled.
>
> cn1:~ # rsh filer df -h vol1
> Filesystem total used avail capacity Mounted on
> /vol/vol1/ 2448GB 776GB 1671GB 32% /vol/vol1/
> snap reserve 612GB 158GB 453GB 26% /vol/vol1/..
>
> So according to this we have 156GB worth of snapshots. So far so good.
>
> cn1:~ # rsh filer snap delta vol1
>
> Volume vol1
> working...
>
> ...
>
> Summary...
>
> From Snapshot To KB changed Time Rate (KB/hour)
> --------------- -------------------- ----------- ------------ --------------
> Oldest_snap Active File System 265800060 14d 09:08 770120.583
>
> Oops. I would expect df -h to show *more* than snap delta (due to the fact that we have more intermediate snapshots); but how comes that - apparently having 260GB worth of snapshot data - I only see 158GB in space accounting?
>
> I am likely missing something obvious. Hmm ... is it possible that "snap delta" accounts for both changed *and* new data while "df -h" accounts for *changed* data only? Looks plausible...
Snapshot accounting can be very tricky I think. Consider this scenario.
1) take snapshot #1 of a volume
2) create a new and very large file
3) take snapshot #2 of volume
4) delete the very large file
5) take snapshot #3
At this point the "delta" between snapshots 1 and 3 and the live volume
will be very small. But the "delta" between snapshot 2 and any other
snapshot (or the live volume) will be large. This is because snapshot 2
(and only snapshot 2) still contains the large file that was deleted.
So you can see that the delta between the live volume and each of
its snapshots does not necessarily increase with the age of the snapshot.
Steve Losen scl@virginia.edu phone: 434-924-0640
University of Virginia ITC Unix Support