Diagnosing the state of a software RAID

Requirements:


If you think there is a problem with the software RAID on your server:

  1. Reboot the server in rescue mode.
  2. Connect yourself to your server using SSH
  3. Switch to the root user using the sudo command (“sudo su”)

To view the current state of the RAID type the following command:

cat /proc/mdstat

If everything is in good condition, you will see something like the following output:

Personalities : [linear] [raid0] [raid1] [raid6] [raid5] [raid4] [multipath] [faulty] 

md1 : active raid1 sdb2[1](W) sda2[0]
 976125376 blocks [2/2] [UU]

md0 : active raid1 sdb1[1] sda1[0]
 96320 blocks [2/2] [UU]

unused devices: <none>

If there is a problem with the raid the letters [UU] will be displayed as [U_] or [_U]

Personalities : [linear] [raid0] [raid1] [raid6] [raid5] [raid4] [multipath] [faulty]

md1 : active raid1 sdb2[1](W) sda2[0]
 976125376 blocks [2/2] [_U]

md0 : active raid1 sdb1[1] sda1[0]
 96320 blocks [2/2] [_U]

unused devices: <none>

In case of a problem, continiue by checking the status of the disks .

In case of need, you may also contact the support.