We are running redundant FWSMs in two 7613 routers in multiple context mode. The FWSMs are configured for Active/Standby failover. We were deleteing several contexts in the Primary FWSM in an effort to reclaim some unused licenses and they suddenly failed over. Could we have inadvertently triggered the failover by deleting too many contexts, and associated interfaces, too quickly? Has anyone ever experienced anything like this?
failover interface-policy 1
That line right there says that even if one interface fails the unit will failover.
If the number of failed interfaces meets the configured policy and the other FWSM is functioning properly, the FWSM will mark itself as failed and a failover may occur (if the active FWSM is the one that fails). Only interfaces that are designated as monitored by the monitor-interface command count towards the policy.
Now, the question is how many interfaces are you monitoring? "sh run monitor" - output.
We do see quite a few postmortem cases without the necessary data for us to arrive at a root cause. Without all the data we can only guess...
I am sure you would have smartnet and if so, you are welcome to open a TAC case where we can take the time to put your config in the lab and see if we can do the same context/interface removing that you did to see the behavior.