ZFS v28 and free space leakage
peter.maloney at brockmann-consult.de
Fri Mar 30 16:33:42 UTC 2012
I think you ran zpool list... Does zfs list show the same?
Do you have any snapshots or clones?
What sort of vdevs do you have?
Does creating an empty pool show 0 used? What about after adding more
Do you have datasets? They might use some for metadata.
Here begins the guessing and/or babbling...
And I haven't tried this with zfs, but I know with ext on Linux, if you
fill up a directory, and delete all the files in it, the directory takes
more space than before it was filled (du will include this space when
run). So be very thorough with how you calculate it. Maybe zfs did the
same thing with metadata structures, and just left them allocated empty
(just a guess).
To prove there is a leak, you would need to fill up the disk, delete
everything, and then fill it again to see if it fit less. If I did such
a test and it was the same, I would just forget about the problem.
Perhaps another interesting experiment would be to zfs send the pool to
see if the destination pool ends up in the same state.
On 30.03.2012 16:49, Volodymyr Kostyrko wrote:
> Hi all.
> Maybe I'm missing something, but when I delete all data from the disk
> how much space should empty disk occupy?
> kohrah1 136G 22,6M 136G 0% 1.00x ONLINE -
> I.e. I have 22 hidden megs. Scrub doesn't touch them. There were no
> snapshots. Disk was deduped in the past. Server hit core dump several
> times when running bonnie++ over deduped ZFS.
> If I create a snapshot and dump it down it would be 50 Kb file.
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