Failover for the Redis server

High availability in Redis is achieved through master-replica replication.

A master Redis server can have multiple Redis servers as replicas, preferably deployed on different nodes across multiple data centres. When the master is unavailable, one of the replicas can be promoted to become the new master and continue to serve data with little or no interruption.

Given the simplicity of Redis, there are many standard high-availability tools available that can monitor and manage a master-replica configuration. However, the most common HA solution that comes bundled with Redis is Redis Sentinels. Redis Sentinels run as a set of separate processes that in combination monitor Redis master-replica sets and provide automatic failover and reconfiguration.

In more recent times Redis introduced support for Redis Clusters. A Redis Cluster provides a way to run a Redis installation where data is automatically sharded across multiple Redis nodes. The WebSEAL remote Redis session cache does not currently provide support for Redis Clusters.