How to redirect if less than x nodes are avail

If you need to use a rule, you can use the command:

active_members 

This will return the number of active pool members in the pool.

Also, you can generate a log entry from the iRule and then add a configuration line to /etc/alertd/alert.conf to have alertd generate an snmp trap for you (you will likely have to restart alertd with "bigstart restart alertd"). Your alert line would look something like this:

 
 alert BIGIP_RULES_RULESERR_RULE "^Rule (.*?): SNMPTRAP" { 
    snmptrap OID=".1.3.6.1.4.1.3375.2.4.0.50" 
 } 
 

The following iRule should then generate the trap.

 
 when HTTP_REQUEST { 
    if { [HTTP::uri] contains "debug" } { 
       log local0. "SNMPTRAP - Request for debug" 
    } 
 }