How do I reinitialise a failed RAID 5 drive using terminal on Ubuntu Server
- by Stephen
I've currently put together a new system and part of that has been creating a software RAID 5 using 'mdadm' in Ubuntu Server.
I successfully got to the point where I create the array using:
sudo mdadm --create --verbose /dev/md0 --level=5 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
I left it to do its thing overnight then used the following command to check on it:
watch cat /proc/mdstat
To which the following was returned:
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid5 sdd1[4](S) sdc1[2] sdb1[1] sda1[0](F)
5860535808 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/2] [_UU_]
unused devices: <none>
It appears that one has failed (and I'm not too savvy with why another is a spare).
So, just to be sure that something else isn't amiss I wanted to try and re-engage the failed drive. Can someone explain how I can do that and what I should do with the spare (if anything).
And also how do I know when synchronisation is complete?
The tutorial I used to get this far is located here:
http://sonniesedge.co.uk/2009/06/13/software-raid-5-on-ubuntu-904/
Many thanks!
p.s. Here is some extra information that may help:
sudo mdadm --detail /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Mon Jun 18 21:14:21 2012
Raid Level : raid5
Array Size : 5860535808 (5589.04 GiB 6001.19 GB)
Used Dev Size : 1953511936 (1863.01 GiB 2000.40 GB)
Raid Devices : 4
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Mon Jun 18 21:50:26 2012
State : clean, FAILED
Active Devices : 2
Working Devices : 3
Failed Devices : 1
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Name : myraidbox:0 (local to host myraidbox)
UUID : a269ee94:a161600c:fb1665e7:bd2f27b3
Events : 13
Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 17 1 active sync /dev/sdb1
2 8 33 2 active sync /dev/sdc1
3 0 0 3 removed
0 8 1 - faulty spare /dev/sda1
4 8 49 - spare /dev/sdd1
