IP_MONITOR versus monitored_subnet

[Randolph Knippel]

Why are Subnet monitors specified at both the Cluster and Package levels in ServiceGuard? Are there 2 monitors, or does it just have to be enabled in both configurations to work?

I noticed that I can turn IP_MONITOR to OFF and get a successful cmcheckconf without eliminating the monitored_subnet in the package configuration. And the reverse is also true- a successful cmcheckconf after eliminating monitored_subnet from the package but without changing the cluster configuration from IP_MONITOR ON.

Also cmcheckconf allows me to eliminate monitored_subnet from the package without changing local_lan_failover_allowed from 'yes' to 'no' despite the fact that the latest documentation says that 'local_lan_failover_allowed   yes' requires that monitored_subnet be specified.

I am looking at disabling the subnet monitor because both of our nodes are on the same subnet. Recently that subnet has experienced some brief outages that has caused failover/failback to occur by virtue of the subnet monitoring. The resulting outage caused by failover/failback ended up being longer than the newtork outage.