https://github.com/racker/rackspace-monitoring-agent-plugins-contrib/blob/master/megaraid.sh

#!/bin/bash
	# Rackspace Cloud Monitoring Plug-In
	# megaraid plugin to query SMART status of drives attached to LSI megaraid or
	# DELL PERC {3,700} raid controllers.
	#
	# ----------------------------------------------------------------------------
	# "THE BEER-WARE LICENSE" (Revision 42):
	# <simon.vetter@runbox.com> wrote this file. As long as you retain this notice
	# you can do whatever you want with this stuff. If we meet some day, and you
	# think this stuff is worth it, you can buy me a beer in return
	# ----------------------------------------------------------------------------
	#
	# Usage:
	# Place plug-in in /usr/lib/rackspace-monitoring-agent/plugins
	#
	# This plugin returns 5 metrics:
	# - failed : the number of drives in failed state,
	# - prefail : the number of drives in prefail state,
	# - unknown : the number of drives for which the smart state could not
	# be determined,
	# - ok : the number of drives in OK state,
	# - report : a string reporting the drive id, vendor, serial number
	# as well as the smart state for non-ok drives.
	# e.g. /dev/bus/0 -d megaraid,4 SEAGATE 6SL28GNF FAILED \
	# ^controller & drive ids ^vendor ^serial# ^state
	# ( HARDWARE IMPENDING FAILURE GENERAL HARD DRIVE FAILURE [asc=5d, ascq=10] )
	# ^SMART health status for this drive
	#
	# The following is an example 'criteria' for a Rackspace Monitoring Alarm:
	#
	# if (metric['failed'] != 0) {
	# return new AlarmStatus(CRITICAL, '#{failed} failed drive(s): #{report}');
	# }
	#
	# if (metric['prefail'] != 0) {
	# return new AlarmStatus(WARNING, '#{prefail} prefail drive(s): #{report}');
	# }
	#
	# if (metric['unknown'] != 0) {
	# return new AlarmStatus(WARNING, '#{unknown} unknown drive(s): #{report}');
	# }
	#
	# return new AlarmStatus(OK, '#{ok} drive(s) OK');
	#
	# Things to keep in mind:
	# - this plugin needs a fairly recent version of smartmontools (tested OK with 6.2)
	# (apt-get install smartmontools) but does NOT need megacli.
	# - on big and loaded arrays, the plugin can take more than 10s (default agent plugin
	# timeout) to complete. Some disks are slower than others, not surprisingly.
	# - as of now, this plugin only checks individual drives and not the status of the
	# array as seen by the controller. I'd add it, but it seems hard to extract without
	# megacli which I'm trying to stay away from. If you know of a way, please let me
	# know.
	#
	#
	SMARTCTL=$(which smartctl)
	OK_CNT=0
	PREFAIL_CNT=0
	FAILED_CNT=0
	UNKNOWN_CNT=0
	REPORT=""
	# discover all drives
	DEVLIST=$(${SMARTCTL} --scan 2>/dev/null)
	if [ $? -ne 0 ]
	then
	echo status failed to perform drive discovery
	exit 1
	fi
	while read DEV
	do
	STAT=$(${SMARTCTL} ${DEV} --info --health 2>/dev/null)
	STATRC=$?
	SHS=$(echo "${STAT}" | grep -i 'smart health status:' | cut -d':' -f2)
	DRIVE_ID=$(echo "${STAT}" | grep -iE '(vendor:|serial number:)' | cut -d':' -f2 | xargs)
	# Bit 3: SMART status check returned "DISK FAILING".
	if [ $((${STATRC} & (2**3))) -ne 0 ]; then
	((FAILED_CNT++))
	REPORT="${REPORT} ${DEV} ${DRIVE_ID} FAILED (${SHS} ) "
	# Bit 4: We found prefail Attributes <= threshold.
	# Bit 5: SMART status check returned "DISK OK" but we found that some (usage or prefail)
	# attributes have been <= threshold at some time in the past.
	elif [ $((${STATRC} & (2**4) | ${STATRC} & (2**5))) -ne 0 ]; then
	((PREFAIL_CNT++))
	REPORT="${REPORT} ${DEV} ${DRIVE_ID} PREFAIL (${SHS} ) "
	# Anything else (drive open failed, smart command failed, etc.) maps to unknown to me
	elif [ ${STATRC} -ne 0 ]; then
	((UNKNOWN_CNT++))
	REPORT="${REPORT} ${DEV} ${DRIVE_ID} UNKNOWN (${SHS} ) "
	else
	((OK_CNT++))
	fi
	# only care for /dev/bus devices. /dev/sd* are logical disks
	# and do not respond to any SMART command.
	done < <(echo "${DEVLIST}" | grep /dev/bus/ | cut -d'#' -f1)
	if [ "z${REPORT}" == "z" ]; then
	REPORT="all drives OK"
	fi
	echo "status smart status retrieved"
	echo "metric failed uint32 ${FAILED_CNT}"
	echo "metric prefail uint32 ${PREFAIL_CNT}"
	echo "metric unknown uint32 ${UNKNOWN_CNT}"
	echo "metric ok uint32 ${OK_CNT}"
	echo "metric report string ${REPORT}"
	exit 0