#!/bin/bash
# mdadm --monitor event handler, by Jan Ceuleers
# Licence: GPL v2
# Handles SparesMissing event. Uses blkid output to find devices that have
# the same UUID as the RAID device, but which are not yet members of the array.
# Have this script executed by mdadm by passing its name to the mdadm --monitor
# daemon using the --program parameter.
# On Debian-like systems this can be accomplished like so:
#   echo "DAEMON_OPTIONS=\"\$DAEMON_OPTIONS --program /pathto/script\"" >> /etc/default/mdadm

BLKID="/sbin/blkid"
MDADM="/sbin/mdadm"

(
  case $1 in
    SparesMissing)
      COMPUUID=`$MDADM  -D $2 | grep UUID | cut -f 2 -d 'D' | cut -f 3 -d ' '`
      COMPUUID2=${COMPUUID//:/}
      COMPUUID3=${COMPUUID2:0:8}-${COMPUUID2:8:4}-${COMPUUID2:12:4}-${COMPUUID2:16:4}-${COMPUUID2:20}
      echo The UUID of component devices is $COMPUUID \($COMPUUID3\)
      blkid | grep $COMPUUID3 | grep linux_raid_member | (
        while read l; do
          COMPDEV=`echo $l | cut -f 1 -d ':'`
          $MDADM -D $2 | grep $COMPDEV > /dev/null
          if [ $? -eq 0 ] ; then
            echo Device $COMPDEV is already a member of the array
          else
            echo Found device $COMPDEV with the same UUID but not yet a component device.
            $MDADM $2 --add $COMPDEV 2>&1
          fi
        done
      )
      ;;
    *)
      echo "Unknown event type; can't handle."
      ;;
  esac

) | mail -s "Handling $1 mdadm event on $2" root