what happens if LB_FAILED is not handled

does client automatically retry by itself?

 

 

or is "Reselect Tries" configured?

 

 

However, beginning in BIG-IP version 10.x it is possible to cause a reselection by using the Reselect Tries advanced pool feature. This feature is equivalent to the LB::reselect iRule command. Once a connection attempt to a pool member is considered failed (equivalent to the LB_FAILED iRule event), the BIG-IP system selects a new pool member. Should that pool member also fail, the system repeats the reselection until it reaches the limit configured for this option. Only at this point is the client connection reset.sol10640: Pool member reselection options

 

http://support.f5.com/kb/en-us/solutions/public/10000/600/sol10640.html

 

 

just my 2 cents.