Heartbeat and Ldirectord may log some messages to syslog with a priority of LOG_DEBUG. For the purposes of debugging, to ensure that these, and all other messages produced will be logged to disk by syslog add the following to /etc/syslog.conf. Note that the default facility used is local0. This is configurable in the ha.cf file and the syslog configuration should match.
Once this is done restart syslogd. If syslog was installed as a package this may be done using the syslog init script.
/etc/init.d/sysklogd restart Stopping system log daemon: syslogd. Starting system log daemon: syslogd.
On Red Hat Enterprise Linux 3:
/etc/init.d/syslog restart Shutting down kernel logger: [ OK ] Shutting down system logger: [ OK ] Starting system logger: [ OK ] Starting kernel logger: [ OK ]
Otherwise, this may done by sending syslogd a SIGHUP to the running syslogd process.
killall -HUP syslogd
If heartbeat looses communication with another node then it will mark the node as unavailable. If the loss of communication occurs because of a communication-media failure, for example the only ethernet link connecting two nodes is unplugged, then both nodes will mark each other as unavailable and take over resources.
In the case of IP address takeover this may result in two machines having the same IP address. This should not be critical as the nodes can't communicate with the network anyway. Once network communication is restored then heartbeat should resolve this and only one node will have the virtual IP address. However, for some resources - for instance shared disk - this may be a critical problem.
The best way to avoid this is to make sure that communication-media failures do not occur by having multiple links between nodes. One or more ethernet links and one or more null-modem links is recommended. It is generally advisable to configure Heartbeat to communicate over all available links.
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Last Updated: Sat Mar 4 16:33:57 2006 +0900
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