CARP on backup doesn't relinquish MASTER

[Rudy Rucker]

I noticed that if I reboot a server that is the MASTER, the carp0 on the 
BACKUP box goes into MASTER mode and stays that way -- even when the 
real master machine has finished rebooting.  Is this a desired trait to 
prevent CARP from switching IPs out of control?

Any how, I wrote a cronjob that runs once an hour on the slave.  If if 
finds itself in the MASTER mode on a carp device, it up/down's the 
interface to get it back into the BACKUP mode.

Rudy




#!/bin/sh
# 
------------------------------------------------------------------------------
# should_be_backup_carp.sh
# 
------------------------------------------------------------------------------
# Check to make sure a carp device is in the backup state.
# Run this as an hourly CRON on the 'backup' machine.
#
# If the Backup machine is found in the 'MASTER' state, this script will 
cycle
# the CARP device in an attempt to let the other device regain MASTER 
status.
# (for some reason, when the MASTER reboots, it does not reassert itself as
#  the MASTER on my system.)
#
# If you accidentally install this script on the MASTER server, you will get
# some not so good results.  :)
#
# THIS SOFTWARE IS PROVIDED BY Rudy ``AS IS'' AND WARRANTIES ARE DISCLAIMED.
# Rudy Rucker, Jr. -  2007

# Usage:
# Check carp0 (default) only:
#	0 * * * * /path/should_be_backup_carp.sh
# Check multiple devices:
#	0 * * * * /path/should_be_backup_carp.sh carp0 carp2 ...

# 
------------------------------------------------------------------------------

if [ -n "$1" ]; then
	for D in $@; do
		_DEV=$D
		export _DEV
		$0
	done
	exit;
fi

DEV=${_DEV:=carp0}
#DEBUG=YES

STATE=`/sbin/ifconfig ${DEV:?"Error you must define a DEV"} 2> /dev/null 
| /usr/bin/grep vhid | /usr/bin/awk '{print $2}'`
STATE=${STATE:?"Error finding state for $DEV."}

if [ $STATE = 'MASTER' ]; then
	
	echo "${HOST:=`/bin/hostname`} is $STATE on $DEV."
	echo "This script is going to cycle interface in attempt to relinquish 
MASTER status."
	echo "If this is not desired on $HOST, remove $0 from the crontab."
	echo
	echo "IFCONFIG before cylce:"
	/sbin/ifconfig $DEV
	/sbin/ifconfig $DEV down;
	sleep 3;
	echo
	echo "IFCONFIG during cylce:"
	/sbin/ifconfig $DEV
	/sbin/ifconfig $DEV up;
	sleep 3;
	echo
	echo "IFCONFIG after cylce:"
	/sbin/ifconfig $DEV
elif  [ $STATE != 'BACKUP' ]; then
	echo "Something is ill configured with $0"
	echo "${HOST:=`/bin/hostname`} is $STATE on $DEV."
	echo
	echo "I don't know what the state '$STATE' is all about."
elif [ -n "$DEBUG" ]; then
	echo "${HOST:=`/bin/hostname`} is $STATE on $DEV."
fi