On Sun, 9 Aug 2009 20:43:34 +1000 (EST) "NeilBrown" <neilb@xxxxxxx> wrote: > > The remaining drives: sdb and sdd, are slot '0' and '1' though I suspect > you expected them to be '1' and '3'. > As they are 0 and 1, they don't provide all of the data. > You need to figure out which slot sdc3 used to occupy and recreate > the array using 'missing' for the fourth drive and '--assume-clean' > to avoid resync. > e.g. mdadm -S /dev/md2 > mdadm --create /dev/md2 --level 10 --layout f2 --assume-clean \ > /dev/sdb3 /dev/sdd3 missing /dev/sdc3 > That is assuming that you figure out that sdc3 was slot '3' (counting > from 0). > > The only way I can think of to find out where sdc3 was slot 2 or > slot 3 is to try each of them and then run a 'check' and see what > the mismatch count is. > > So run the above --create command, but don't fsck or mount or anything > else to the device. > Then echo check > /sys/block/md2/md/sync_action > and watch the value of > /sys/block/md2/md/mismatch_cnt > > if that keeps getting big, the we picked the wrong slot. > If it stays fairly small (maybe a few hundred) then we probably got the > right slot. > To try the other arrangement, use the same command except for the last > two words which should be swapped: /dev/sdc3 missing > > Once you have the array working again with 3 disks, choose a disk > to remove that will leave the array still functional. For a 4 disk > raid10 in f2, you need either both even devices (0 and 2) or both > odd devices (1 and 3). > > Then continue with your original plan. > --re-add should work if you have picked the right drive and have a > bitmap. > > > Good luck. > > NeilBrown > It worked. BIG THANKS! The working combination was: mdadm --create /dev/md2 --level 10 --layout f2 -c 4096 --assume-clean \ --raid-devices 4 /dev/sdb3 /dev/sdd3 missing /dev/sdc3 -- <daniel.iliev@xxxxxxxxx> -- 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
