Suggest an editImprove this articleRefine the answer for “What is Redis Cluster?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)Redis Cluster is a Redis mode where data is automatically distributed across several nodes by hash slots (16384 slots in total, each master owning its own range), to provide scaling and fault tolerance; every master has one or several replicas, which automatically take over the master role on failure. **Key point:** the client determines a key's slot using the CRC16 hash function, and if that slot belongs to a different master, it gets a MOVED response and is redirected; not every command is supported (e.g. `MULTI/EXEC` with keys spread across different slots), and some data can become temporarily unavailable if a master and all its replicas fail.Shown above the full answer for quick recall.Answer (EN)Image**Redis Cluster** is a Redis mode where data is automatically **distributed across several nodes** (server instances), to provide **scaling and fault tolerance**. ### The core idea In plain Redis, all data lives on a single server. In Redis Cluster, keys are split across nodes by **hash slots** (16384 slots in total). Every master node is responsible for a specific range of slots. Example: ```javascript master1 → slots 0-5460 master2 → slots 5461-10922 master3 → slots 10923-16383 ``` ### Architecture - Every **master** holds part of the data. - Every master has one or several **replicas**. - Replicas automatically take on the master role if the primary node fails. So: ```javascript master1 → replica1 master2 → replica2 master3 → replica3 ``` ### How this works 1. The client connects to any node in the cluster. 2. The node figures out which slot the key belongs to (via the CRC16 hash function). 3. If that slot belongs to a different master, it returns a **MOVED** response, and the client is redirected to the right node. 4. If a master fails, one of its replicas automatically becomes the new master. ### What Redis Cluster gives you - **Horizontal scaling**, nodes can be added, and data gets redistributed. - **Fault tolerance**, if a master fails, its replica takes over. - **Automatic routing**, clients know where to look for a given key. ### Limitations - Not every command is supported (e.g. `MULTI/EXEC` with several keys spread across different slots). - It requires a properly cluster-aware client driver. - Some data can become temporarily unavailable if a master and all its replicas fail. ### Summary > Redis Cluster is a distributed system built into Redis, > where data is split into 16384 slots across several masters with replicas, > providing **scaling, fault tolerance, and automatic recovery** with no external tools like Sentinel needed.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.