Sentinel configuration in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Redis Sentinel used for?

Redis Sentinel is used to monitor Redis servers, automatically failover to a replica if the master fails, and provide high availability.

beginner

Which configuration directive defines the master Redis server in Sentinel?

The sentinel monitor directive defines the master Redis server that Sentinel will monitor.

intermediate

What does the sentinel down-after-milliseconds setting control?

It controls how long Sentinel waits before marking a master as down if it does not respond.

intermediate

How does Sentinel decide to perform a failover?

Sentinel performs a failover when it detects the master is down and a majority of Sentinels agree the master is unreachable.

intermediate

What is the purpose of the sentinel auth-pass directive?

It sets the password Sentinel uses to authenticate with the Redis master or replicas if they require authentication.

Which command in Sentinel configuration specifies the master to monitor?

A sentinel failover-timeout

B sentinel auth-pass

C sentinel down-after-milliseconds

D sentinel monitor

The sentinel monitor command tells Sentinel which master Redis server to watch.

What happens if Sentinel detects the master is down?

A It immediately deletes the master data

B It restarts the master server automatically

C It waits for a majority of Sentinels to agree and then triggers failover

D It ignores the failure

Sentinel waits for consensus among Sentinels before starting failover to ensure reliability.

Which setting controls how long Sentinel waits before marking a master as down?

A sentinel down-after-milliseconds

B sentinel failover-timeout

C sentinel parallel-syncs

D sentinel auth-pass

sentinel down-after-milliseconds sets the timeout for marking a master as down.

What does sentinel auth-pass configure?

A Password for Sentinel to authenticate with Redis servers

B Password for clients connecting to Redis

C Password for Sentinel web interface

D Password for Redis replication

It sets the password Sentinel uses to authenticate with monitored Redis servers.

How many Sentinels must agree a master is down to trigger failover?

A One Sentinel

B A majority of Sentinels

C All Sentinels

D No agreement needed

A majority agreement ensures failover is triggered only when truly necessary.

Explain the main steps Sentinel takes to detect a master failure and perform failover.

Think about how Sentinel watches the master and what happens when it stops responding.

Describe the key configuration directives used in Redis Sentinel and their purpose.

Focus on directives that control monitoring, failover, and security.