Fantastic! I ran the following command: mdadm --assemble /dev/md10 --verbose --force --run /dev/loop0 /dev/loop1 /dev/loop2 and it returned mdadm: looking for devices for /dev/md10 mdadm: /dev/loop0 is identified as a member of /dev/md10, slot 0. mdadm: /dev/loop1 is identified as a member of /dev/md10, slot 1. mdadm: /dev/loop2 is identified as a member of /dev/md10, slot 2. mdadm: forcing event count in /dev/loop0(0) from 81589 upto 81626 mdadm: forcing event count in /dev/loop2(2) from 81589 upto 81626 mdadm: added /dev/loop1 to /dev/md10 as 1 mdadm: added /dev/loop2 to /dev/md10 as 2 mdadm: no uptodate device for slot 6 of /dev/md10 mdadm: added /dev/loop0 to /dev/md10 as 0 mdadm: /dev/md10 has been started with 3 drives (out of 4). I can mount /dev/md10 and I have access to my data. Now that I know my data is safe. I need to restart the original array on the server. The array is completely deactivated on the original server. The company that I rent the dedicated server from is waiting for my GO to replace disk sdd with a new one. I'm giving then the GO now. After I reboot the server, what is it I need to do to rebuild sdd as the fourth disk of the array? Regards ------------------------- Santiago DIEZ Quark Systems & CAOBA 23 rue du Buisson Saint-Louis, 75010 Paris ------------------------- On Sat, Oct 22, 2016 at 12:35 AM, Shaohua Li <shli@xxxxxxxxxx> wrote: > On Fri, Oct 21, 2016 at 10:45:10AM +0200, Santiago DIEZ wrote: >> Hi, >> >> Thanks Andreas, >> >> Yes apparently, 3/4 of the original disks seem to be safe. But I'm >> terrified at the idea of doing something wrong assembling them. >> Incidentally, I indeed did a mistake trying to assemble the ddrescue >> images of the 3 safe disks. I tried to create again with proper >> metadata and chunck but it did not work. I'm still scared at the idea >> of restarting the original raid. I'm currently ddrescuing again the 3 >> partitions to then try and *assemble* them rather than *create*. >> >> >> Thanks Wol, >> >> I use loop devices because I work on partition images, not on actual partitions: >> I use ddrescue to copy data from /dev/sd[abc]10 to >> some.other.server:/home/sd[abc].img >> Then I go to some.other.server and turn the images into loop devices : >> losetup /dev/loop0 /home/sda10.img >> losetup /dev/loop1 /home/sdb10.img >> losetup /dev/loop2 /home/sdc10.img >> Then I tried to created the raid, it worked but as I said, the >> filesystem was unreadable. >> I know the idea of using loop devices works because I tested it before. >> I'm doing the whole procedure all over again (takes 5 days to ddrescue >> the 3 partitions to another server) and then I will use the command >> you recommended : >> mdadm --assemble /dev/md0 /dev/loop0 /dev/loop1 /dev/loop2 --force >> >> >> Will keep you posted >> >> ------------------------- >> Santiago DIEZ >> Quark Systems & CAOBA >> 23 rue du Buisson Saint-Louis, 75010 Paris >> ------------------------- >> >> On Mon, Oct 10, 2016 at 12:39 AM, Wols Lists <antlists@xxxxxxxxxxxxxxx> wrote: >> > >> > On 08/10/16 13:30, Andreas Klauer wrote: >> > > On Fri, Oct 07, 2016 at 05:37:32PM +0200, Santiago DIEZ wrote: >> > >> > First thing I did is ddrescue the remaining partitions sd[abc]10 . >> > >> > ddrescue did not stumble into any read error so I assume all remaining >> > >> > partitions are perfectly safe. >> > > So ... don't you still have a good copy? >> > > >> > > You only killed one of them, right? Did not make same mistake twice? >> > > >> > >> > There comes my mistake: I ran the --create command instead of --assemble : >> > >> > >> > >> > ================================================================================ >> > >> > # mdadm --create --verbose /dev/md1 --raid-devices=4 --level=raid5 >> > >> > --run --readonly /dev/loop0 /dev/loop1 /dev/loop2 missing >> > >> > One oddity I've noticed. You've created the array using loop devices. >> > What are these? >> > >> > The reason I ask is that using loopback devices is a standard technique >> > for rebuilding a damaged array, specifically to prevent md from actually >> > writing to the drive. So is it possible that "mdadm --create" only wrote >> > to ram, and a reboot will recover your ddrescue copies untouched? >> > >> > My raid-fu isn't enough to tell me whether I'm right or not ... :-) >> > >> > If necessary you'll have to do another ddrescue from the original >> > drives, and you should then be able to assemble the array from the >> > copies. Don't use "missing", use "--force" and you should get a working, >> > degraded, array to which you can add a new drive and rebuild the array. >> > >> > mdadm --assemble /dev/md0 /dev/sd[efg]10 --force >> > >> > if I'm right ... so long as it's the copies, you can always recover >> > again from the original disks, and if there's a problem with the copies >> > mdadm should complain when it assembles the array. > > Hmm, those commands work for me. I'm adding Song and Jes if they have ideas. > > Thanks, > Shaohua -- 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
