RAID notes

From Koset Surakomol

My home file server

On one or two occasions, the array simply lost a member. I got this warning by email: pre DegradedArray event on /dev/md1 ... A DegradedArray event had been detected on md device /dev/md1.

Faithfully yours, etc.

P.S. The /proc/mdstat file currently contains the following:

Personalities : [raid1] [raid6] [raid5] [raid4] md1 : active raid5 sdb3[1] sdc3[2]

    954742784 blocks level 5, 64k chunk, algorithm 2 [3/2] [_UU]

md0 : active raid1 sda1[0] sdc1[1]

    10008384 blocks [2/2] [UU]

unused devices: none /pre

To fix it, I simply rebooted and issued this command: pre $ mdadm -a /dev/md1 /dev/sda3 /pre

This shows the progress: pre mdadm --detail /dev/md1 /pre

Output: pre /dev/md1:

       Version : 0.90
 Creation Time : Wed Jan 23 05:52:31 2008
    Raid Level : raid5
    Array Size : 954742784 (910.51 GiB 977.66 GB)
 Used Dev Size : 477371392 (455.26 GiB 488.83 GB)
  Raid Devices : 3
 Total Devices : 3

Preferred Minor : 1

   Persistence : Superblock is persistent

   Update Time : Tue Mar  3 17:42:09 2009
         State : clean, degraded, recovering
Active Devices : 2

Working Devices : 3

Failed Devices : 0
 Spare Devices : 1

        Layout : left-symmetric
    Chunk Size : 64K

Rebuild Status : 7% complete

          UUID : 2cd08adc:93a93bc4:ca3961b7:c57b82c0
        Events : 0.228210

   Number   Major   Minor   RaidDevice State
      3       8        3        0      spare rebuilding   /dev/sda3
      1       8       19        1      active sync   /dev/sdb3
      2       8       35        2      active sync   /dev/sdc3

/pre