Forcing a Heartbeat Failover with Mon

Another method to accomplish a failover is to run Mon on the LVS Director and force the LVS Director to release all of its resources using the hb_standby program when Mon detects that something has gone wrong. (The Heartbeat package comes with the hb_standby program.)

By running Heartbeat and Mon on the LVS Director, you can initiate a Heartbeat failover with a Mon alert script that executes the hb_standby program.

Note 

Heartbeat will not stop resources in a resource group (recall that a resource group is a list of resources on a single line in Heartbeat's /etc/ha.d/haresources file) when the hb_standby program is used to initiate a failover. To avoid a possible split brain condition, you must use Stonith.

SOPHISTICATED SNMP MONITORING

A more sophisticated SNMP monitoring technique than the method described in this chapter is available to you when you use the Mon monitoring script called snmpvar.monitor. This script is available for download from the Mon contrib page of the Mon website at http://www.kernel.org/software/mon.

The snmpvar.monitor script allows you to specify SNMP variables along with their associated minimum and maximum values in a configuration file (snmpvar.cf). The snmpvar.monitor script can then check the SNMP variables on a remote host and tell Mon to raise an alert if a value falls outside of the range you specify.

If you need help with installing the snmpvar.monitor monitoring script (or if you have any questions about Mon), you can post your question to the Mon mailing list at http://www.kernel.org/software/mon/list.html.