Optimal timeout and interval settings for Apache health monitor

Some enterprising people have cooked up solutions based on this irule event https://devcentral.f5.com/wiki/iRules.lb_failed.ashx

I won't be able to write such an irule for you, but the idea is, for your critical apps, you use that event to detect when a connection sent to a particular pool member fails, and then attempt to select a new member instead of propagating the failure back to the client. You would use some kind of counter to make sure you don't fall into the pit of infinite repetition (if all pool members are down, a naive irule will continue trying to select a new member indefinitely until a pool member is available, so you use a counter that limits reselection attempts to maybe 3, and then propagate the failure back to the client).

If this is not too much work for your requirements, then enjoy the challenge.