Adam Sweet's Wiki

Below are some notes on using Linux Software RAID. It's not complete yet of course :)

Marking a damaged disk as failed:

mdadm --manage --set-faulty /dev/md1 /dev/sdd1

Removing the damaged disk from the array:

mdadm /dev/md1 -r /dev/sdd1

Shutdown your system, bring it up into single user mode and partition and format your new disk. Set the partition type as Linux Software RAID autodetect. Of course you need to partition your new disk the same as the previous one. Bring the machine up into it's default runlevel, either by rebooting or by doing init 5 or init 2 depending on your Linux distribution.

Add your new disk to the array:

mdadm /dev/md1 -a /dev/sdd1

Viewing the status of the array (the one shown here is repairing):

[root@host ~]# cat /proc/mdstat Personalities : [raid1] md1 : active raid1 sdc1[2] sdd1[1]

    142327744 blocks [2/1] [_U]
    [==========>..........]  recovery = 54.5% (77655168/142327744) finish=65.2min speed=16503K/sec

md0 : active raid1 sdb1[1] sda1[0]

    142327744 blocks [2/2] [UU]
    

unused devices: <none>

Showing status detail for a particular array:

[root@jet ~]# mdadm --detail /dev/md1

/dev/md1:

      Version : 00.90.01
Creation Time : Sat Jan 13 08:24:54 2007
   Raid Level : raid1
   Array Size : 142327744 (135.73 GiB 145.74 GB)
  Device Size : 142327744 (135.73 GiB 145.74 GB)
 Raid Devices : 2
Total Devices : 2

Preferred Minor : 1

  Persistence : Superblock is persistent

  Update Time : Wed Aug 27 09:10:48 2008
        State : clean, degraded, recovering

Active Devices : 1 Working Devices : 2 Failed Devices : 0

Spare Devices : 1

Rebuild Status : 55% complete

  Number   Major   Minor   RaidDevice State
     0       0        0       -1      removed
     1       8       49        1      active sync   /dev/sdd1
     2       8       33        0      spare   /dev/sdc1
         UUID : cb59fcb5:d61a134b:3e799237:ab0c3b4f
       Events : 0.25582871

Linux Software RAID Howto http://www.networknewz.com/2003/0113.html http://acd.ucar.edu/~fredrick/linux/fedoraraid/