In Conclusion

This chapter used a "test" resource script to demonstrate how Heartbeat starts a resource and fails it over to a backup server when the primary server goes down. We've looked at a sample configuration using the three configuration files /etc/ha.d/ha.cf, /etc/ha.d/haresources, and /etc/ha.d/authkeys. These configuration files should always be the same on the primary and the backup servers to avoid confusion and errant behavior of the Heartbeat system.

The Heartbeat package was designed to failover all resources when the primary server is no longer healthy. Best practices therefore dictate that we should build multiple physical paths for heartbeat status messages in order to avoid unnecessary failovers. Do not be tempted to use the production network as the only path for heartbeats between the primary and backup servers.

The examples in this chapter did not contain an IP address as part of the resource configuration, so no Gratuitous ARP broadcasts were used. Neither did we test a client computer's ability to connect to a service running on the servers.

Once you have tested resource failover as described in this chapter (and you understand how a resource script is called by the Heartbeat program), you are ready to insert an IP address into the /etc/ha.d/haresources file (or into the iptakeover script introduced in Chapter 6). This is the subject of Chapter 8, along with a detailed discussion of the /etc/ha.d/haresources file.