I have a Debian Wheezy with 3 Partitions as RAID6. MD0 is for Root and OS, MD1 is for SWAP and MD2 for Files. While copy files to MD2 the system reports kernel panic and halts. I have had shutdown on the hard way. When I boot the system I get the message:

md0: cannot start dirty degraded array
md0: failed to run raid set
failed to run_array md0 inpu/output error
md0 is already in use
gave up waiting for root device common problems...
alert! dev/disk/by-uuid/eb8r..... does not exist.
dropping to a shell!
cant access tty job control turned off

proc/mdstat shows for md0 missing Partion sdg2. mdadm detail shows:

Raid Devices: 7
Total Devices: 6
Active D: 6
Working: 6
0...active sync sda2
6 removed sdf2

I am unsure what to do.

  • I do examine to sdg2 and it is good, shows 7xArray State A but only 6 active. What should i do now? – Sunghost Apr 29 '14 at 21:35
  • Thx, ok i presently not in front of the server, but i will now run a mdadm --assemble --force /dev/md0 /dev/sda2 /dev/sdb2 /dev/sdc2 /dev/sdd2 /dev/sde2 /dev/sdf2 missing <- hope that will work. – Sunghost Apr 30 '14 at 9:22
  • I could rescue the raid. -stop the md0 - assemble over all drives - add missing two drives - rebuild over 18h and its started – Sunghost May 7 '14 at 7:52

Restore from backup.

The next time you build the machine, make md0 RAID1 and only the large data stores RAID6.

Or better, invest in a hardware RAID card.

  • Hi,sorry no backup and no money for external Raid Card. I know the facts but SW-Raid is a good Option too. Raid1 was one of my thought, but i decided to use raid6 for all 3 partitions due to simplicity. I cant understand why the raid dies while only one out of 7 partitions failed ? Raid6 should cach them and run, or not? How ever the initial question is how could i rebuild / rescue the raid? – Sunghost Apr 30 '14 at 9:00
  • At this point I'd strongly advise not doing it yourself and getting someone familiar with software RAID in to assist. If you can, first make a backup of all the disks. – MikeyB Apr 30 '14 at 14:22
  • “…no backup and no money for external Raid Card.” Seems like the money not spent at the beginning is going to end up costing you more in the end. Ounce of prevention. – JakeGould Apr 30 '14 at 15:21

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