THANKS! \o/

Thanks so much for posting all this info!

It’s very likely I didn’t loose any more data…

Namely, while one drive wqas failing, it corrupted the raid (there some loss of date, but not much), but, and(the following is the exact reason I chose raid10 over raid5) I was left with 4 out of 6 sevices woking (back some two years ago on raid5 I lost data in similar one and one more drive failure).

By backing up the devices as I explained above, I found out that I could smoothly back up (and that the data would be fine gzipped date) on /dev/sda6 /dev/sdc6 /dev/sdd6 /dev/sdf6 (but input/output error showed up soon on /dev/sdb6, and sde6 was a partition on a failed disk, that I replaced.

I examined the disks from FreeDOS with SeaTools (Seagate and other disks they are), and the disks were no errors (long test).

So I did (#myCMNT is my comment and it’s history lines from Gentoo LiveCD):

#myCMNT Didn't do.
   58  mdadm -A /dev/md3 /dev/sda6 /dev/sdc6 /dev/sdd6 /dev/sdf6
#myCMNY Did do.
   59  mdadm -A /dev/md3 /dev/sda6 /dev/sdc6 /dev/sdd6 /dev/sdf6 --force
   60  mdadm /dev/md3 -a /dev/sde6
#myCMNT Started rebuild.
   61  mdadm -D /dev/md3
   77  mdadm /dev/md3 -a /dev/sdb6</pre>

I already saw the data are there. And while I am writing this I only have to wait for the last partition to have raid10 rebuilt with on.

   77  mdadm /dev/md3 -a /dev/sdb6
/dev/md3:
 ...
    Array Size : 606227968 (578.14 GiB 620.78 GB)
  Used Dev Size : 151556992 (144.54 GiB 155.19 GB)
...
          State : clean, degraded, recovering
 Active Devices : 5
Working Devices : 6
 Failed Devices : 0
  Spare Devices : 1

     Chunk Size : 128K

 Rebuild Status : 41% complete
...

    Number   Major   Minor   RaidDevice State
       0       8       38        0      active sync   /dev/sdc6
       1       8       70        1      active sync   /dev/sde6
       2       8       86        2      active sync   /dev/sdf6
       3       8       54        3      active sync   /dev/sdd6
       4       8        6        4      active sync   /dev/sda6
       6       8       22        5      spare rebuilding   /dev/sdb6

I’m glad if this helps anybody who turns up seeking solution for a similar problem…

Cheers!

First I am backing up the very devices the raid10 (of some 500GB of rather useful data… months of work lost if that raid is gone).

That raid10 is assembled of 6 partitions: sd[a-f]6 on 6 200GB drives

I think here can still be found out how to do it.

The commands that I’ll be using will be six commands of the form:

dd if=/dev/sdX6 | gzip -6c  | split -d -b1085m - backup_2009-01-01_sdX6.dd

where capital X needs to be replaced by letter a, next command letter b, and so on through f.

E.g., to back up device /dev/sda6, I’ve now issued:

dd if=/dev/sda6 | gzip -6c  | split -d -b1085m - 2009-01-01_sda6.dd

It’ll be taking loooong, but much greater extent than that length and labor will be the time and the work saved an secured from harm, in case I mess up that 500-GB-of-data raid10. as I’ll be able to start over from scratch…

In case someone feels it’s the right kind of backup, here you can read more.

I’ll let you know if and when and how I recovered these data, this raid10…

Cheers

Nick

I knew the other two disks were ok so I went for the --assume-clean option and it worked!

PHEW again. I’d have committed suicide if I had lost that data. You don’t keep unimportant data on a raid array

thanks