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Ive got an Problem with my JBOD, after my Synology DS died because of the failure of the Boot-HDD, ive wanted to recover my JBOD (3x3TB). Ive Started an Debian-Live to mount and save the data from my Jbod, that worked well.

I Ordered an 8Tb drive from amazon to save the data, but as i started the Rsync Job the middle Device (sdb) got i/o errors... My Fault was to think a reboot would help because of an unhandled Kernel error... Ye, dumb me, the middle Disk died.

My Problem now: Ive got the first and the last device working but mdadm said:

root@debian:~# mdadm --assemble --force /dev/md3 /dev/sd[bc]3

mdadm: /dev/md3 assembled from 2 drives - not enough to start the array.


Thats the Drives:

root@debian:/# mdadm --examine /dev/sd[abc]3 /dev/sdb3:

      Magic : a92b4efc

    Version : 1.2

Feature Map : 0x0

 Array UUID : e8937ad2:c0080cf8:6e96733a:2a3b4ee8

       Name : LG-NAS:3

Creation Time : Sat Feb 25 20:08:20 2017

 Raid Level : linear

Raid Devices : 3

Avail Dev Size : 5850889088 (2789.92 GiB 2995.66 GB)

Used Dev Size : 0

Data Offset : 2048 sectors

Super Offset : 8 sectors

Unused Space : before=1968 sectors, after=32 sectors

      State : clean

Device UUID : baa0a4e4:9bc55ee7:6e6d27ea:fe158da8

Update Time : Thu Mar  9 15:20:28 2017
   Checksum : 84051d55 - correct
     Events : 1
   Rounding : 64K

Device Role : Active device 0 Array State : AAA ('A' == active, '.' == missing, 'R' == replacing)


/dev/sdc3:

      Magic : a92b4efc

    Version : 1.2

Feature Map : 0x0

 Array UUID : e8937ad2:c0080cf8:6e96733a:2a3b4ee8

       Name : LG-NAS:3

Creation Time : Sat Feb 25 20:08:20 2017

 Raid Level : linear

Raid Devices : 3

Avail Dev Size : 5850889088 (2789.92 GiB 2995.66 GB)

Used Dev Size : 0

Data Offset : 2048 sectors

Super Offset : 8 sectors

Unused Space : before=1968 sectors, after=32 sectors

      State : clean

Device UUID : 0b4313db:8989392c:870a02d2:910a8eb5


Update Time : Thu Mar  9 15:20:28 2017

   Checksum : b42b1540 - correct

     Events : 1

   Rounding : 64K

Device Role : Active device 2 Array State : AAA ('A' == active, '.' == missing, 'R' == replacing)

root@debian:/# fdisk -l /dev/sd[abc]3

Disk /dev/sdb3: 2.7 TiB, 2995656278016 bytes, 5850891168 sectors

Units: sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes


Disk /dev/sdc3: 2.7 TiB, 2995656278016 bytes, 5850891168 sectors

Units: sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes

root@debian:/# mdadm --examine --scan ARRAY /dev/md/3 metadata=1.2 UUID=e8937ad2:c0080cf8:6e96733a:2a3b4ee8 name=LG-NAS:3

My Last Idea now, to recreate the JBOD using the Following command:

mdadm --create --verbose /dev/md3 --name=LG-NAS:3 --metadata=1.2 --level=linear --raid-devices=3 /dev/sdb3 missing /dev/sdc3

Or

mdadm --create --verbose /dev/md3 --name=LG-NAS:3 --metadata=1.2 --level=linear --raid-devices=2 /dev/sdb3 /dev/sdc3

Any suggestions what to do next?

  • Synology is bad news. – ewwhite Jun 8 '17 at 21:29
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A JBOD has no redundancy at all.

If the failed disks is somewhat accessible (ie: it has not catastrophically failed) I would ddrescue it onto another, working disk (with at least the same capacity). At this point, you can try to forcefully restart the array with the new disk replacing the old one.

If this does not work, you had to photorec your disks to extract as much data as possible.

  • Hi, thanks for the answer, the secound disk isnt accessible, i've got an HP Microserver gen8, and the disk isnt showing up in the Intelligent Provisioning... I'll try photorec for the 2 remaining devices and see what happens... – Leonard G. Jun 9 '17 at 23:33

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