jay@xxxxxxxxxxxxxxxxxxxxxxxxx (jay@xxxxxxxxxxxxxxxxxxxxxxxxx) wrote on 21 April 2008 16:20: >Quoting Carlos Carvalho <carlos@xxxxxxxxxxxxxx>: > >> jay@xxxxxxxxxxxxxxxxxxxxxxxxx (jay@xxxxxxxxxxxxxxxxxxxxxxxxx) wrote >> on 20 April 2008 18:35: >> >I had a single disk failure in a 3-disk RAID5 array recently, and have >> >been trying to reassemble the array with the remaining devices, but am >> >running into some issues. >> > >> >The failed disk died during synchronization into the array, >> >> Did another one fail during the resync? If not you can try to >> reassemble the array with only the 2 good disks using --force. > >The array did fall offline shortly after the first failure, which >seemed unexpected; the two remaining disks (and controller) still seem >healthy (states 'clean' and 'active' respectively), just that they >refuse to assemble. You should check the logs to see the cause. >> If a second disk failed you're in trouble. Since the array stopped at >> the moment of the second failure, the two disks are still in sync. >> Well, almost... You can then make an image of the second failed disk >> on a good one and use --force to reassemble again. Then fsck... > >This sounds good - the only filesystem mounted over the devices was >read-only at the time, so I'm hoping that the two good disks should >still be enough for some data recovery. > >The only problem I see is that if I make a raw image copy of the >second disk, it will still have the incorrect 'slot' assignment in the >superblock. I suppose I could dd everything except the superblock - >but is there a mechanism to repair/recreate the superblock on a raw >disk? No, just assemble with --force. >The other idea I have in mind is to - after a backup - recreate the >array using the initial configuration (raid-level 5, num-devices 3, >etc), and hope that the array can pick itself up again. > >Any thoughts much appreciated - thanks for helping out :) This is the last alternative, when you're sure the 2 disks are fine. Then just re-create the array replacing the /dev/3rd-drive by the word "missing". This won't change the data, it'll just re-write the superblocks. Then do read-only fsck -- 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
