Saving the RAID May 22, 2008
Posted by idimmu in linux.I managed to screw up my home machine when upgrading from Dapper to Hardy somehow, so decided to flatten and reinstall Hardy from scratch.
This is all well and good but I have a RAID 5 array on my machine which stores all my important documents and stuff (I really hate drive failure). Ubuntu didn't suddenly detect my RAID array and figure everything out, which was not entirely unsurprising but was a little scary.
After some light reading, and a few sighs and heart flutters I worked out the magic runes to tell the system I have a RAID array, where it was and how to use it!
root@server:/root# mdadm -A /dev/md0 -v /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/sde
mdadm: looking for devices for /dev/md0
mdadm: /dev/sda is identified as a member of /dev/md0, slot 0.
mdadm: /dev/sdb is identified as a member of /dev/md0, slot 1.
mdadm: /dev/sdc is identified as a member of /dev/md0, slot 2.
mdadm: /dev/sdd is identified as a member of /dev/md0, slot 3.
mdadm: /dev/sde is identified as a member of /dev/md0, slot 4.
mdadm: added /dev/sdb to /dev/md0 as 1
mdadm: added /dev/sdc to /dev/md0 as 2
mdadm: added /dev/sdd to /dev/md0 as 3
mdadm: added /dev/sde to /dev/md0 as 4
mdadm: added /dev/sda to /dev/md0 as 0
mdadm: /dev/md0 has been started with 5 drives.
root@server:/root# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sda[0] sde[4] sdd[3] sdc[2] sdb[1]
976793600 blocks level 5, 128k chunk, algorithm 2 [5/5] [UUUUU]
unused devices: <none>
root@server:/root# mdadm -Es
ARRAY /dev/md0 level=raid5 num-devices=5 UUID=19c77b42:c5e86159:c23e7b08:7f8ceabd
