On Jan 22, 2008 12:29 AM, Mike Snitzer <snitzer@xxxxxxxxx> wrote: > cc'ing Tanaka-san given his recent raid1 BUG report: > http://lkml.org/lkml/2008/1/14/515 > > > On Jan 21, 2008 6:04 PM, Mike Snitzer <snitzer@xxxxxxxxx> wrote: > > Under 2.6.22.16, I physically pulled a SATA disk (/dev/sdac, connected to > > an aacraid controller) that was acting as the local raid1 member of > > /dev/md30. > > > > Linux MD didn't see an /dev/sdac1 error until I tried forcing the issue by > > doing a read (with dd) from /dev/md30: .... > The raid1d thread is locked at line 720 in raid1.c (raid1d+2437); aka > freeze_array: > > (gdb) l *0x0000000000002539 > 0x2539 is in raid1d (drivers/md/raid1.c:720). > 715 * wait until barrier+nr_pending match nr_queued+2 > 716 */ > 717 spin_lock_irq(&conf->resync_lock); > 718 conf->barrier++; > 719 conf->nr_waiting++; > 720 wait_event_lock_irq(conf->wait_barrier, > 721 conf->barrier+conf->nr_pending == > conf->nr_queued+2, > 722 conf->resync_lock, > 723 raid1_unplug(conf->mddev->queue)); > 724 spin_unlock_irq(&conf->resync_lock); > > Given Tanaka-san's report against 2.6.23 and me hitting what seems to > be the same deadlock in 2.6.22.16; it stands to reason this affects > raid1 in 2.6.24-rcX too. Turns out that the aacraid driver in 2.6.22.x is HORRIBLY BROKEN (when you pull a drive); it responds to MD's write requests with uptodate=1 (in raid1_end_write_request) for the drive that was pulled! I've not looked to see if aacraid has been fixed in newer kernels... are others aware of any crucial aacraid fixes in 2.6.23.x or 2.6.24? After the drive was physically pulled, and small periodic writes continued to the associated MD device, the raid1 MD driver did _NOT_ detect the pulled drive's writes as having failed (verified this with systemtap). MD happily thought the write completed to both members (so MD had no reason to mark the pulled drive "faulty"; or mark the raid "degraded"). Installing an Adaptec-provided 1.1-5[2451] driver enabled raid1 to work as expected. That said, I now have a recipe for hitting the raid1 deadlock that Tanaka first reported over a week ago. I'm still surprised that all of this chatter about that BUG hasn't drawn interest/scrutiny from others!? regards, Mike - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
