On 6-Jun-10, at 7:11 AM, Thomas Maier-Komor wrote:
On 06.06.2010 08:06, devsk wrote:
I had an unclean shutdown because of a hang and suddenly my pool is
degraded (I realized something is wrong when python dumped core a
couple of times).
This is before I ran scrub:
pool: mypool
state: DEGRADED
status: One or more devices has experienced an error resulting in
data
corruption. Applications may be affected.
action: Restore the file in question if possible. Otherwise
restore the
entire pool from backup.
see: http://www.sun.com/msg/ZFS-8000-8A
scan: scrub repaired 0 in 0h7m with 0 errors on Mon May 31 09:00:27
2010
config:
NAME STATE READ WRITE CKSUM
mypool DEGRADED 0 0 0
c6t0d0s0 DEGRADED 0 0 0 too many errors
errors: Permanent errors have been detected in the following files:
mypool/ROOT/May25-2010-Image-Update:<0x3041e>
mypool/ROOT/May25-2010-Image-Update:<0x31524>
mypool/ROOT/May25-2010-Image-Update:<0x26d24>
mypool/ROOT/May25-2010-Image-Update:<0x37234>
//var/pkg/download/d6/d6be0ef348e3c81f18eca38085721f6d6503af7a
mypool/ROOT/May25-2010-Image-Update:<0x25db3>
//var/pkg/download/cb/cbb0ff02bcdc6649da3763900363de7cff78ec72
mypool/ROOT/May25-2010-Image-Update:<0x26cf6>
I ran scrub and this is what it has to say afterwards.
pool: mypool
state: DEGRADED
status: One or more devices has experienced an unrecoverable
error. An
attempt was made to correct the error. Applications are
unaffected.
action: Determine if the device needs to be replaced, and clear the
errors
using 'zpool clear' or replace the device with 'zpool
replace'.
see: http://www.sun.com/msg/ZFS-8000-9P
scan: scrub repaired 0 in 0h11m with 0 errors on Sat Jun 5
22:43:54 2010
config:
NAME STATE READ WRITE CKSUM
mypool DEGRADED 0 0 0
c6t0d0s0 DEGRADED 0 0 0 too many errors
errors: No known data errors
Few of questions:
1. Have the errors really gone away? Can I just clear and be
content that errors are really gone?
2. Why did the errors occur anyway if ZFS guarantees on-disk
consistency? I wasn't writing anything. Those files were definitely
not being touched when the hang and unclean shutdown happened.
I mean I don't mind if I create or modify a file and it doesn't
land on disk because on unclean shutdown happened but a bunch of
unrelated files getting corrupted, is sort of painful to digest.
3. The action says "Determine if the device needs to be replaced".
How the heck do I do that?
Is it possible that this system runs on a virtual box? At least I've
seen such a thing happen on a Virtual Box but never on a real machine.
As I postulated in the relevant forum thread there:
http://forums.virtualbox.org/viewtopic.php?t=13661
(can't check URL, the site seems down for me atm)
The reason why the error have gone away might be that meta data has
three copies IIRC. So if your disk only had corruptions in the meta
data
area these errors can be repaired by scrubbing the pool.
The smartmontools might help you figuring out if the disk is broken.
But
if you only had an unexpected shutdown and now everything is clean
after
a scrub, I wouldn't expect the disk to be broken. You can get the
smartmontools from opencsw.org.
If your system is really running on a Virtual Box I'd recommend that
you
turn of disk write caching of Virtual Box.
Specifically, stop it from ignoring cache flush. Caching is irrelevant
if flushes are being correctly handled.
ZFS isn't the only software system that will suffer inconsistencies/
corruption in the guest if flushes are ignored, of course.
--Toby
Search the OpenSolaris forum
of Virtual Box. There is an article somewhere how to do this. IIRC the
subject is somethink like 'zfs pool curruption'. But it is also
somewhere in the docs.
HTH,
Thomas
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