Redis high availability and load balancing
Redis Sentinel will allow you to run multiple instances of redis and handles failover for you. http://redis.io/topics/sentinel
An obvious solution to loadbalance redis is to use sentinel.
As far as I can see predis does not support sentinel as of now. See:
https://github.com/nrk/predis/issues/131
A possible solution can be Redis sentinel + HAProxy failover if you want to keep using predis.