Similar to Lasse's RAID 5 array, I have 3 1TB drives. And the same problem as Lasse with an array stopped working for one reason and can't recover for another reason. And what about badblocks? After an upgrade to Ubuntu 10.04 I had at first NO (visible) raid array at all. After a short investigation it turned out that /dev/sdd was "busy"-something, which I now have figured out must have been an attempt to recover. Unfortunately I hadn't understood all sides of running a RAID when I started to act on the problem, so I may accidentally have destroyed my chances to recover this in the end, but lets see... mdadm /dev/md0 --detail (as well as with --examine) shows 0 ... active sync /dev/sdb1 1 ... active sync /dev/sdc1 2 ... faulty removed (shows only with --examine) 3 ... spare /dev/sdd1 I can't tell when /dev/sdd1 went from number 2 to 3. It's never been outside the computer. So I began to consider the /dev/sdd1 as actually faulty. And as so, I started to think of ways to recover. First, a complete backup, and after that I also tried mdadm -a /dev/md0 /dev/sdd1 and as a result the number 3 disk started to rebuild. Here comes the interesting part; after 35% the recovering halted/exited due to sector fault on /dev/sdb1 and consequently disabling /dev/sdb1. This leaves the RAID5 with only one disk and very unhappy to recover the 3rd /dev/sdd1. Now, here is the strange(?) thing. Checking the array while having it run with only two disks (sdb1 and sdc1) I could (and still can) access all files without any (as seen so far) errors. I haven't written anything to the disk, except for that the timestamps may have changed. (so I took the chance and have now made a complete backup) My guess is that the stored information (so far 12% of disk capacity) has been away from the bad sectors and therefor also contains correct info. When recovering the sdd1 and coming up to the faulty sectors (for what ever reason it wants to access those at recover) it can no longer hold the array as clean and therefor stops with "Disk failure on sdb1, disabling the device." This leads to a problem. I have 3 disks, where one (the first event) (disk sdd1) fell out of sync (reason unknown). And therefor needs to (at least claims to need) rebuild of sdd1. But it can't, since sdb1 is faulty. Even though no data is placed on the bad sectors. So, I have two disks that together holds enough information to rebuild the third, but do not complete the task due to errors on sectors not in use... ... hm... Would it be possible to copy (with 'dd') the device (/dev/sdb) with sector errors to a fourth disk (/dev/sde) and then remove the faulty sdb-drive and reposition the newly copied sde to sdb's position to have this act as the first sdb-drive, now working without any physical faults, even if the data is incomplete in sectors; and now being possible to recover the third drive (/dev/sdd1)? Lasse: > ... How do i proceed from here? On which device should i run badblocks? Is this at all possible on a md-device? Isn't this what Neil is working on? Or is it by any chance any meaning to run badblocks on an empty drive just to catch bad sectors? Would mdadm by any chance use them when creation is done? /Carl Wagner -- 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
