Load Balancing between 2 Pool (Failover on 2 different pool)

Hi My requirement:- as per today my income traffic hits on VIP 1 which is mapped with X number of pool members , in case of unavailability of all pool member traffic should shift to another pool which has x number of pool member.

Can anyone provide me solution, if the solution is with irule then help me with script.

Regards Suhail Nedaria