With a good hard disk drive, a very small USB flash drive for L2ARC, an old USB hub, Mountain Lion and with a series of very aggressive hot unplugs etc.: I created a situation where the kernel would panic every time the hard disk drive was connected. Maybe relevant:
- the mistreatments coincided with multiple concurrent scrubs, one of which was for the two drives mentioned above:
Strings that were common to the panic reports included:
"/staging/zevo/src/uts/common/fs/zfs/spa.c:1277 ZFS assertion failed: 0 == dmu_bonus_hold(spa->spa_meta_objset, obj, FTAG, &db)"@/staging/zevo/src/uts/darwin/os/printf.c:43
BSD process name corresponding to current thread: zpool
Details withheld because, amongst other things, the series of actions was not suitably recorded.
I opted to destroy the affected pool, then restore from a very recent backup.