Perform a health check on a redirecting irule

From the looks of you iRule, since you're not doing any kind of checking to whether the node is available, you will run into problems.

Check out the wiki pages for pool, LB::status, and the iRules 101 page for help on doing these kinds of checks.

Then I'd suggest testing the status of the node, and you may even want to look at the LB_FAILED event to re-select a different node in case there's an issue.