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This article explains how to manually migrate a hash slot in a Redis cluster by checking cluster status, setting importing and migrating slots, retrieving keys, using the MIGRATE command, and updating slot assignments across nodes, with detailed command examples and explanations.
This article analyzes the latency and availability problems of native Redis cluster slot migration, proposes a master‑slave synchronization based redesign that batches slot transfers, reduces ask‑move and topology‑change overhead, and validates the solution with performance tests showing smoother latency and higher reliability.
This article analyzes a Redis cluster outage caused by a slot‑migration bug where a node simultaneously migrated slots in and out, leading to conflicting config epochs, gossip‑protocol mismatches, and MOVED errors, and provides detailed troubleshooting steps and preventive measures.
Vivo’s storage team redesigned Redis cluster slot migration by disguising the target as a slave and using master‑slave replication with progressive loading, which eliminates ask‑move round trips, reduces latency spikes, consolidates topology updates, and ensures stable access and high availability during horizontal scaling.
An in‑depth, timeline‑driven investigation of a production Redis memory leak revealed that the custom 3.2.8 build’s getKeysInSlot function failed to free a temporary key‑array after traversing the radix‑tree, causing hundreds of megabytes of leaked SDS strings, which was fixed by adding a single free call and highlighted the need for functional code reviews and early leak detection.
Redis Cluster is a distributed system that partitions its keyspace into 16,384 hash slots across up to 16,384 nodes, enabling automatic sharding, slot migration, replication, and high‑availability features such as automatic node discovery, master‑slave election, and online resharding without service interruption.