Checking node status from iRules

Yes, Brian, you are correct on this. When a persist entry is used, it is first checked to see whether the resulting pool member is still active. If it is not still active, the persist entry will be replaced after the connection is re-load-balanced. This sounds like it should handle the scenario.

 

 

If they are interested in more specifically controlling the node that gets selected in the event the node is down, you could write a rule that would first do the persist lookup and node select, then if the connection failed to that node (because the node is down), you could pick the new node using whatever mechanism you want (in the LB_FAILED rule event). (I should also add that when the node in the persist entry is down, the LB_FAILED event is not triggered - it's treated more like there was no persist entry to begin with).