Panic on ZFS startup after crash

[Daniel Eriksson]

I have a large ZFS pool that seems to be partially corrupt, causing a
panic on ZFS startup. This is on a RELENG_7_0 machine.

This is what happens when I try to start ZFS (written down by hand):

ZFS: WARNING: can't process intent log for tank02/home
ZFS: WARNING: can't process intent log for tank02
panic: solaris assert: dmu_read(os, smo->smo_object, offset, size,
entry_map) == 0 (0x5 == 0x0), file:
/usr/src/sys/modules/zfs/../../contrib/opensolaris/uts/common/fs/zfs/spa
ce_map.c, line: 341

The pool sits on top of a geli-encrypted hardware raid-array (Highpoint
RocketRAID 2340, 8 x 500GB in RAID-5 config). Unfortunately the array
broke (2 drives disconnected) due to a bad PSU, and this eventually
crashed the box. When I restarted the box the above message showed up as
soon as I started ZFS.

It is my understanding that the intent log is emptied on clean shutdown,
and if it is not empty during startup ZFS tries to "replay" the
transactions recorded in it. I assume the initial crash left the intent
log in an inconsistent state and that ZFS panics on startup due to badly
formatted data in the intent log.

Is there any way I can recover this pool?


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Daniel Eriksson (http://www.toomuchdata.com/)