On Mon, 29 Nov 2010 18:24:18 +0100 Michele Bonera <mbonera@xxxxxxxxx> wrote: > Hi all. > > I'm a little bit in panic... and I really need some help to solve this > (if possible......)... > > I have a storage server in my LAN where I save everything > for security (sigh). > > The system consists in a 32 GB SSD containing the o.s. > plus 4 WD EADS 1TB harddisks in RAID5 with all my data. > The disks are seen by the system as sdb1, sdc1, sdd1, sde1 > > Yesterday evening I added another WD, this time an EARS > (512 byte sectors): I created a partition on it, respecting the > alignment and then I added it to the array and performed a > grow command > > mdadm --add /dev/md6 /dev/sdb1 (after adding it, the hd took sdb) > mdadm --grow /dev/md6 --raid-devices=5 > > Reshape started... and worked until today. Or better, until the system > hangs and I have to sync+remount-ro with the sysrq keys. > > After rebooting, the reshaping restarted, but the disk become sdb > not sdb1 in the raid array, and the file system became unreadable > > Any ideas of what happened? Yes. I think you can fix it by simply failing and removing sdc Then md/raid5 will recover that data using the parity block, and that should be correct. It appears that the partition you created on the new device started at a multiple of 64K. When this happen, the superblock at the end of the partition also looks valid when seen at the end of the whole device. Somehow mdadm got confused and choose the whole device (sdc) instead of the partition (sdc1). I am surprised at this because since mdadm-2.5.1, mdadm will refuse to assemble an array if it sees two devices that appear to have the same superblock. Could you possibly be using something that old?? So when the reshape started, it was writing data for the 5th device to sdc1. Then after you restared, it was writing data for the 5th device to sdc, which the same drive of course, but at a different offset. So everthing that was written before the crash will look wrong. So the thing to do is to stop md from reading from sdc at all, as that device is clearly corrupt. So just fail and remove it. Then add it back in again. If you do re-partition, try to make sure sdc1 does not start at a multiple of 64K (128 sectors). NeilBrown -- 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
