RAID Disc Scrubbing

Linux RAID with MDAM:

• Software RAID Howto
• Data Scrubbing of RAID Array
• Keep RAID Array Healthy
• Why You Should Your RAID Arrays Regularly
• Arch Wiki RAID Maintenence
• How Often to Do Data Scrubbing

View status of RAID arrays:

# cat /proc/mdstat 
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md11 : active raid1 sda2[2] sdb2[3]
      488058688 blocks super 1.2 [2/2] [UU]
      
md10 : active raid1 sda1[2] sdb1[3]
      194368 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>

Check Hardrives:

1. RAID Scrubbing

2. Use S.M.A.R.T

RAID Scrubbing: (Very Simple Method)

• Data Scrubbing Gentoo Wiki

"With a modern kernel, >=2.6.16, this command will initiate a data consistency check and a unreadable block check: reading all blocks, checking them for consistency, and attempting to rewrite unreadable blocks:"

echo check >> /sys/block/mdX/md/sync_action

• RAID Gentoo Wiki

"In short: Especially if you run a RAID5 array, trigger an active bad block check on a regular basis, or there is a high chance of hidden bad blocks making your RAID unusable during reconstruction."

Notice this version is different to the method in the blog. This one works.

#!/bin/bash
for f in /sys/block/md* ; do 
    echo check > $f/md/sync_action
done

# echo check >> /sys/block/md10/md/sync_action

# echo check >> /sys/block/md11/md/sync_action

View process:

 cat /proc/mdstat

One Liner to see RAID Arrays:

# for f in /sys/block/md*;do echo $f;done;

/sys/block/md10
/sys/block/md11

Configure MDADM to notify server admin when there is something wrong with one of the hardrives:

sudo vim /etc/mdadm/mdadm.conf

The sysadmin's email should be in this config file:

# This is /etc/mdadm/mdadm.conf
MAILADDR admin@example.com
ARRAY /dev/md/10 metadata=1.2 UUID=04040873:f375aaea:8dbdb090:cf7c93fa name=ubuntu:10
ARRAY /dev/md/11 metadata=1.2 UUID=51a93042:65a1dafe:20a0a873:a94a518e name=ubuntu:11

MDADM also has its own built in checking but only happens one Sunday of each month:

# /etc/cron.d/mdadm
57 0 * * 0 root if [ -x /usr/share/mdadm/checkarray ] && [ $(date +\%d) -le 7 ]; then /usr/share/mdadm/checkarray --cron --all --idle --quiet;fi

I think that the script /usr/share/mdadm/checkarray does several checks on hardrives including data scrubbing.