Restoring a software RAID 1 on Linux

March 12, 2007

When one of the hard disks in a RAID 1 gets out of the RAID because it is no longer in sync with the other disk, you can easily resynchronize it with the following command:

raidhotadd /dev/mdX /dev/sdY

X and Y should be set to the appropriate values.

‘cat /proc/mdstat’ would tell you if your RAID system is healthy.

The configuration of your RAID is set in the file /etc/raidtab which will tell you the disks in the RAID and you can compare the results with the cat command above to see which disk is missing.

I use this script to verify if all disks in my RAID 1 are working fine:


#!/bin/bash
#Check if both drive are up
if [ `grep [UU] /proc/mdstat | wc -l` != 2 ] || [ `grep "2/2" /proc/mdstat | wc -l` != 2 ]; then
  cat /proc/mdstat
  exit 1
fi
exit 0

More info here.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: