RAID 10 won't assemble

Bubbagump210 · 12-08-2010, 10:10 AM

I have a situation where a box rebooted and "forgot" its software RAID setup. Here is the layout:

Main disk that has grub and the /boot partition

A RAID 10 volume at / with everything else.

Grub processes, the kernel "starts" and then fails when trying to access everything in /.

As a recovery attempt I booted to Knoppix.

The partition layout is as follows:

/dev/hde1 * 1 25 200781 fd Linux raid autodetect
/dev/hde2 26 36267 291113865 fd Linux raid autodetect

/dev/hdf1 242 36483 291113865 fd Linux raid autodetect
/dev/hdf2 * 1 241 1935801 fd Linux raid autodetect

/dev/hdg1 * 1 25 200781 fd Linux raid autodetect
/dev/hdg2 26 36267 291113865 fd Linux raid autodetect

/dev/hdh1 242 36483 291113865 fd Linux raid autodetect
/dev/hdh2 * 1 241 1935801 fd Linux raid autodetect

My RAID 10 is made up of /dev/hde2, /dev/hdf1, /dev/hdg2, and /dev/hdh2

In Knoppix I have run

# modprobe md
# mdadm --examine --scan > /etc/mdadm/mdadm.conf

Output looks like:

Code:

ARRAY /dev/md0 level=raid1 num-devices=2 UUID=6b60a409:23bc50ac:dc2b204c:ef5d2cd3

ARRAY /dev/md2 level=raid10 num-devices=4 UUID=b209a118:62760902:cdbbd73f:a6e41fb8

ARRAY /dev/md1 level=raid1 num-devices=2 UUID=364c8a59:438e7372:a5be47de:d442581d

Then I ran

# mdadm --assemble -f -R /dev/md2 /dev/hde2 /dev/hdf1 /dev/hdg2 /d ev/hdh1

Which gives me the error:

mdadm: cannot open device /dev/hde2: Device or resource busy
mdadm: /dev/hde2 has no superblock - assembly aborted

Any ideas how I can get this thing to mount and work?

Bubbagump210 · 12-08-2010, 12:03 PM

Ok, I booted to a newer version of Knoppix and I am getting very different results.

I ran

# mdadm --assemble --run -f /dev/md2 /dev/sda2 /dev/sdb1 /dev/sdc2 /dev/sdd1

With the result

mdadm: no recogniseable superblock on /dev/sda2
mdadm: /dev/sda2 has no superblock - assembly aborted

However, an --examine now shows no data on any partitions.

Is there a similar procedure as with hardware RAID where you can "retag" the drives without data loss?