Interview › Databases & Caching
What is the difference between Redis Sentinel and Redis Cluster?
Databases & Caching · Advanced level
Answer
Sentinel provides failover for one primary dataset without sharding. Redis Cluster provides horizontal sharding plus failover per shard, but requires cluster-aware clients and careful key design.
Technical explanation
Sentinel is simpler when one primary dataset fits on one node and you need failover.
Cluster is used when memory or throughput requires multiple primaries.
Cluster adds client and key-design complexity, especially for multi-key operations.
Hands-on example
Selection example:
20 GB simple cache: primary plus replica with managed failover may be enough.
900 GB tenant cache: cluster mode with shard planning is more appropriate.
Validate client cluster support before choosing Cluster.
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