ZFS and DMA read error

Mark Stapper stark at mapper.nl
Thu Sep 3 09:43:11 UTC 2009

> SpinRite is OK but it hasn't been updated in ages. It does not work on
> large drives. 250GB works, 1TB does not. Haven't tried it on 500GB
> drives.
So it will be useles in... well in this case it IS useles...
> If I were you I would 'zpool offline ...' the offending drive, rewrite
> the entire drive with 'dd if=/dev/zero ...' and then run a SMART
> selftest on it using smartmontools ('smartctl -t long /dev/adX'). When
> you 'zpool online ...' the drive ZFS will resilver it for you. After
> doing all of this I would then run a 'zpool scrub ...'. If the scrub
> finishes without checksum errors and without any ATA-related errors the
> drive is probably in good enough condition to keep using, but watch out
> for more ATA errors. If the drive is dying it won't be long before it
> starts to generate more ATA errors.
Yeah, i did the long SMART selftest three times now, each of which it
failed on the same LBA address.
Did the scrub as well, took two hours, and no DMA errors were reported.
Why would I want to clear my driver before I run these tests?
I ordered a "spare" drive so I'll wait until it arrives, replace the
faulty drive with this one by dd-ing data from one to the other (I have
only 4 SATA ports so I can't do "zpool replace").
Or meybe I'll just swap them out and do "zpool scrub".
I'm uncomfortable doing this though, because if any of the other drives
fails/crashes/flips me off I'll have to restore from my backup which
took two days to make... (which is the drawback of a gzipped zfs backup
Once I've replaced the drive I'll run hitachi's Drive Fitness Test on
the (presumably) failing drive. Even if it doesn't generate any ATA
errors during everyday use, the error it gave before, combined with the
failing SMART self test disturbs me. I bought the drive 2 months ago, so
my faith has gone.
However, if it passes Hitachi's DFT my faith will be restored :-).

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