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Rebuilding Raid
Rebuilding a raid system?
Detail from mdadm of good working file system prior to zeroing the superblock.
<pre> sudo mdadm --detail /dev/md4 /dev/md4:
Version : 0.90
Creation Time : Sat Mar 19 08:02:27 2011
Raid Level : raid6
Array Size : 160649856 (153.21 GiB 164.51 GB)
Used Dev Size : 80324928 (76.60 GiB 82.25 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 4
Persistence : Superblock is persistent
Update Time : Sun Jun 3 21:06:27 2012
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0 Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
UUID : b60f9401:efa1275e:6caba8f0:d8b2a7d7
Events : 0.457
Number Major Minor RaidDevice State
0 8 66 0 active sync /dev/sde2
1 8 82 1 active sync /dev/sdf2
2 8 98 2 active sync /dev/sdg2
3 8 50 3 active sync /dev/sdd2
</pre>
Note, the drive order is very important. Also, remove the ARRAY entry from /etc/mdadm/mdadm.conf for the drive.
<pre> sudo mdadm --stop /dev/md6 sudo mdadm --zero-superblock /dev/sd[defg]2 sudo mdadm --create /dev/md6 --metadata=1.0 --chunk=64 --level=6 --raid-devices=4 /dev/sde2 /dev/sdf2 /dev/sdg2 /dev/sdd2 </pre>
Ok, now we need to get the blkid from the md filesystem and add an entry into the mdadm.conf file which matches.
<pre> sudo blkid /dev/md6 # edit mdadm.conf file and add entry "ARRAY /dev/md6 UUID=dad67a5c:0907045c:7eb49ca0:d0f6f000" sudo mdadm --assemble /dev/md6 --update=resync sudo mdadm --detail /dev/md6 sudo blkid /dev/md6 sudo mount -t ext3 /dev/md6 /mnt/temp
watch -n 1 cat /proc/mdstat </pre>
or... ???
<pre> sudo mdadm --stop /dev/md6 sudo mdadm --zero-superblock /dev/sd[defg]2 sudo mdadm --create /dev/md6 --metadata=0.9 --chunk=64 --level=6 --raid-devices=4 /dev/sde2 /dev/sdf2 /dev/sdg2 /dev/sdd2 sudo mdadm --assemble /dev/md6 --update=resync sudo mdadm --detail /dev/md6 sudo blkid /dev/md6 sudo mount -t ext3 /dev/md6 /mnt/temp </pre>
If this is a new raid drive, make the filesystem then mount
<pre> sudo mkfs /dev/md6 sudo mount /dev/md6 /mnt/temp </pre>