Possible zpool online, resilvering issue

Ultima ultima1252 at gmail.com
Wed Aug 10 16:53:35 UTC 2016


> I didn't see any reply on the list, so I thought I might let you know

Sorry, never received this reply (till now) xD

>what I assume is happening:

> ZFS never updates data in place, which affects inode updates, e.g. if
> a file has been read and access times must be updated. (For that reason,
> many ZFS file systems are configured to ignore access time updates).

> Even if there were only R/O accesses to files in the pool, there will
> have been updates to the inodes, which were missed by the offlined
> drives (unless you ignore atime updates).

> But even if there are no access time updates, ZFS might have written
> new uberblocks and other meta information. Check the POOL history and
> see if there were any TXGs created during the scrub.

> If you scrub the pooll while it is off-line, it should stay stable
> (but if any information about the scrub, the offlining of drives etc.
> is recorded in the pool's history log, differences are to be expected).

> Just my $.02 ...

> Regards, STefan

Thanks for the reply, I'm not completely sure what would be considered a
TXG. Maintained normal operations during most this noise and this pool has
quite a bit of activity during normal operations. My zpool history looks
like it gos on forever and the last scrub is showing it repaired 9.48G.
That was for all these access time updates? I guess that would be a little
less then 2.5G per disk worth.

The zpool history looks like it gos on forever (733373 lines). This pool
has much of this activity with poudriere. All the entries I see are clone,
destroy, rollback and snapshotting. I can't really say how much but at
least 500 (prob much more than that) entries between the last two scrubs.
Atime is off on all datasets.

 So to be clear, this is expected behavior with atime=off + TXGs during
offline time? I had thought that the resilver after onlining the disk would
bring that disk up-to-date with the pool. I guess my understanding was a
bit off.


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