Lasse Kärkkäinen wrote: > I managed to mess up a RAID-5 array by mdadm -adding a few failed disks > back, trying to get the array running again. Unfortunately, -add didn't > do what I expected, but instead made spares out of the failed disks. The > disks failed due to loose SATA cabling and the data inside should be > fairly consistent. sdh failed a bit earlier than sdd and sde, so I > expect to be able to revocer by building a degraded array without sdh > and then syncing. > > The current situation looks like this: > Number Major Minor RaidDevice State > 0 0 8 33 0 active sync /dev/sdc1 > 1 1 0 0 1 faulty removed > 2 2 8 97 2 active sync /dev/sdg1 > 3 3 8 129 3 active sync /dev/sdi1 > 4 4 0 0 4 faulty removed > 5 5 8 81 5 active sync /dev/sdf1 > 6 6 0 0 6 faulty removed > 7 7 8 177 7 spare > 8 8 8 161 8 spare > 9 9 8 145 9 spare > > ... and before any of this happened, the configuration was: > > disk 0, o:1, dev:sdc1 > disk 1, o:1, dev:sde1 > disk 2, o:1, dev:sdg1 > disk 3, o:1, dev:sdi1 > disk 4, o:1, dev:sdh1 > disk 5, o:1, dev:sdf1 > disk 6, o:1, dev:sdd1 > > I gather that I need a way to alter the superblocks of sde and sdd so > that they seem to be clean up-to-date disks, with their original disk > numbers 1 and 6. A hex editor comes to mind, but are there any better > tools for that? You don't need a tool. mdadm --force will do what you want. Read the archives and the man page. You are correct to assemble the array with a missing disk (or 2 missing disks for RAID6) - this prevents the kernel from trying to sync. Not syncing is good because if you do make a slight error in the order, you can end up syncing bad data over good. I *THINK* you should try something like (untested): mdadm --assemble /dev/md0 --force /dev/sdc1 /dev/sde1 /dev/sdg1 /dev/sdi1 missing /dev/sdf1 /dev/sdf1 The order is important and should match the original order. There's more you could do by looking at device event counts (--examine) Also you must do a READ-ONLY mount the first time you mount the array - this will check the consistency and avoid corruption if you get the order wrong. I really must get around to setting up a test environment so I can check this out and update the wiki... I have to go out or a couple of hours. Let me know how it goes if you can't wait for me to get back. David - 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
