How can Redis be configured to ensure high availability and fault tolerance?

To ensure high availability and fault tolerance in Redis, the following approaches are usually used:

1. Replication: Setting up a master and one or more replicas (slaves). Replicas receive a copy of the master's data and can be used for reading, reducing load and providing redundancy.

2. Sentinel: A monitoring and automatic failover system. Sentinel monitors the master’s status and automatically promotes a replica to master in case of failure, ensuring continuous operation.

3. Redis Cluster: A distributed cluster that shards data and provides automatic recovery and load balancing.

Example of Sentinel setup:

• Multiple Sentinel instances are run on different servers.
• The configuration specifies the master and failover parameters.
• Sentinel monitors the master and replicas, and switches roles in case of failure.

Thus, combining replication and Sentinel allows ensuring Redis fault tolerance without data loss and with minimal downtime.