Editing Home systems (section)

== Rebuilding Raid ==
Rebuilding a raid system?

Detail from mdadm of good working file system prior to zeroing the superblock.

&lt;pre&gt;
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
&lt;/pre&gt;

Note, the drive order is very important.
Also, remove the ARRAY entry from /etc/mdadm/mdadm.conf for the drive.

&lt;pre&gt;
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
&lt;/pre&gt;

Ok, now we need to get the blkid from the md filesystem and add an entry into the mdadm.conf file which matches.

&lt;pre&gt;
sudo blkid /dev/md6 # edit mdadm.conf file and add entry &quot;ARRAY /dev/md6 UUID=dad67a5c:0907045c:7eb49ca0:d0f6f000&quot;
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 
&lt;/pre&gt;

or... ???

&lt;pre&gt;
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
&lt;/pre&gt;

If this is a new raid drive, make the filesystem then mount

&lt;pre&gt;
sudo mkfs /dev/md6
sudo mount /dev/md6 /mnt/temp
&lt;/pre&gt;