Version is 7.2.4P6.
С уважением / With best regards / Mit freundlichen Grüβen
--- Andrey Borzenkov Senior system engineer-----Original Message----- From: George T Chen [mailto:gtchen@yahoo-inc.com] Sent: Thursday, May 22, 2008 11:48 PM To: Stephen C. Losen; Borzenkov, Andrey Cc: toasters@mathworks.com Subject: RE: "df -h" shows less snapshots than "snap delta"
What version of OnTap are you running? I have found that versions up to at least 7.1 to be inaccurate in their delta measurement.
> -----Original Message----- > From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] > On Behalf Of Stephen C. Losen > Sent: Thursday, May 22, 2008 4:30 AM > To: Borzenkov, Andrey > Cc: toasters@mathworks.com > 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 > >
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