Redis Senntinel Redis sentinel is a system designed to help managing Redis instances. If you have a single relaese instance and that instance goes down for some reason you are pretty much doomed, because your application depends on Redis to store data. And if your data source is down, your application is out floc to resolve this issue. The primary purpose of using Sentinel is to provide a high availability system by monitoring, notifying and providing intances failover. Sentinel performs 3 tasks. 1- Monitoring: Check if your master and slave instances are working as expected 2. Notification: notify other programs or the system administrator via an API when something goes wrong with tht monitored instances. 3- Automatic faiover: On master failure, sentinel promotes one of the slaves to Master, then makes the other additional slaves use the new master. Sentinel acts as the source of authority for clients. Clients connect to Sentinels in order to ask for the address of the current Redis master At least three Sentinel instances to run on servers that fail in an independent way. Redis client must have Sentinel support.