ZFS deduplication

[Romain Tartière]

On Wed, Jan 23, 2013 at 03:37:29PM +0100, Romain Tartière wrote:
> However, `zpool list` reports an inconsistent deduplication value (it
> used to be ~1.4 AFAICR):
> 
> > zpool list data
> > NAME   SIZE  ALLOC   FREE    CAP  DEDUP  HEALTH  ALTROOT
> > data   460G   101G   359G    21%  1386985.39x  ONLINE  -

Looks like this was some kind of corruption: the system crashed (it has
crashed a few times over the last few months but I could not get details
because of a failing serial port on the machine and the X server was
running) and was then unable to reboot: just after importing the zpool,
the kernel panicked in ddt_phys_decref() trying to dereference a NULL
pointer (because of the serial port I don't have a text backtrace,
however I took a few shots just in case).

I replaced the disks of the pool with new ones, reinstalled FreeBSD and
restored from backup.

I keep the old disks untouched in case some FreeBSD developer involved
in ZFS is interested about this corruption and needs a real-life
corrupted filesystem for analysis.  Please let me know by private mail.

Thanks,
Romain

-- 
Romain Tartière <romain at FreeBSD.org>  http://people.FreeBSD.org/~romain/
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