On Sat, 11 Sep 2010 14:20:40 -0400 Mike Hartman <mike@xxxxxxxxxxxxxxxxxxxx> wrote: > PART 3: > > Update: > > I'm even more concerned about this now, because I just started the > newest reshaping to add a new drive with: > > mdadm --grow -c 256 --raid-devices=5 --backup-file=/grow_md0.bak /dev/md0 > > And the system output: > > mdadm: Need to backup 768K of critical section.. > > cat /proc/mdstat shows the reshaping is proceeding, > > Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] > md0 : active raid6 sdi1[0] sdf1[5] md1p1[4] sdj1[3] sdh1[1] > 2929691136 blocks super 1.2 level 6, 128k chunk, algorithm 2 [5/5] [UUUUU] > [>....................] reshape = 0.0% (56576/1464845568) > finish=2156.9min speed=11315K/sec > > md1 : active raid0 sdg1[0] sdk1[1] > 1465141760 blocks super 1.2 128k chunks > > unused devices: <none> > > but I've checked for /grow_md0.bak and it's not there. So it looks > like for some reason it ignored my backup file option. It didn't. When you making an array larger, you only need the backup file for a small 'critical region' at the beginning of the reshape - 768K worth in your case. Once that is complete the backup-file is not needed and so is removed. So your current situation is no worse that before. [When making an array smaller, the critical section happen and the very end, so mdadm keeps the backup file around - unused - until then. Then uses it quickly and completes. When reshaping an array without changing the size the 'critical section' lasts for the entire time so a backup file is needed and is very heavily used] I don't know yet what is causing the lock-up. A quick look at your logs suggest that it could be related to the barrier handling. Maybe trying to handle a barrier during a reshape is prone to races of some sort - I wouldn't be very surprised by that. I'll have a look at the code and see what I can find. Thanks for the report, NeilBrown > > This scares me, because if I experience the lockup again and am forced > to reboot, without a backup file I'm afraid my array will be hosed. > I'm also afraid to stop it cleanly right now for the same reason. > > So in addition to fixing the lockup itself, does anyone know if > there's a way to either cancel this reshaping or belatedly add the > backup file in a different way so it will be recoverable? It's only at > 1% and says it will take another 2193 minutes. > > Mike > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
