mdadm and degraded arrays

radnoran · 01-10-2010, 03:59 AM

I wasn't sure if this was the right place to post this.

However, I'm currently having issues with an email being sent out about a degraded array.

I've checked through mdadm, and have received the following when I've run commands.

I'm still pretty new to linux, and in-fact, this is the first time I've had to do something with software RAID.

Any idea's on how I remedy the degraded array?

Code:

root@x [~]
root@x [~]# mdadm --detail /dev/md0 --test
/dev/md0:
        Version : 0.90
  Creation Time : Sat Jan  9 06:26:48 2010
     Raid Level : raid1
     Array Size : 225279360 (214.84 GiB 230.69 GB)
  Used Dev Size : 225279360 (214.84 GiB 230.69 GB)
   Raid Devices : 2
  Total Devices : 1
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Sun Jan 10 03:56:38 2010
          State : active, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

           UUID : a361507c:398443c0:4b8636c7:d644af10
         Events : 0.13513

    Number   Major   Minor   RaidDevice State
       0       0        0        0      removed
       1       8       17        1      active sync   /dev/sdb1

root@x [~]# mdadm --detail /dev/md1 --test
/dev/md1:
        Version : 0.90
  Creation Time : Sat Jan  9 06:26:40 2010
     Raid Level : raid1
     Array Size : 16779776 (16.00 GiB 17.18 GB)
  Used Dev Size : 16779776 (16.00 GiB 17.18 GB)
   Raid Devices : 2
  Total Devices : 1
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Sun Jan 10 01:53:32 2010
          State : clean, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

           UUID : d4fb8f39:c65f7e8c:047983be:069e505f
         Events : 0.14

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       0        0        1      removed

# mdadm --query /dev/sda1
/dev/sda1: is not an md array
/dev/sda1: device 0 in 2 device mismatch raid1 /dev/md0.  Use mdadm --examine for more detail.
root@x [~]# mdadm --query /dev/sda2
/dev/sda2: is not an md array
/dev/sda2: device 0 in 2 device active raid1 /dev/md1.  Use mdadm --examine for more detail.
root@x [~]# mdadm --query /dev/sdb1
/dev/sdb1: is not an md array
/dev/sdb1: device 1 in 2 device active raid1 /dev/md0.  Use mdadm --examine for more detail.
root@x [~]# mdadm --query /dev/sdb2
/dev/sdb2: is not an md array
/dev/sdb2: device 1 in 2 device mismatch raid1 /dev/md1.  Use mdadm --examine for more detail.

Thanks.

indienick · 01-11-2010, 01:18 PM

Am I right in assuming that RAID md0 has members sda1 and sdb1, and RAID md1 has members sda2 and sdb2?

If this is the case, just run the following command to re-add the missing members back to their respective RAIDs:

Code:

root# mdadm /dev/md0 -a /dev/sda1
root# mdadm /dev/md1 -a /dev/sdb2

Before you do the commands I've listed above, please post the output of /proc/mdstat. To watch what's happening with the RAID, as it rebuilds, or just in general, issue the following command:

Code:

root# watch -n1 cat /proc/mdstat

To kill this command, just press Ctrl-C.