CLUSTER REPLICATE

CLUSTER REPLICATE node-id turns the receiving node into a replica of the primary with the given ID. The node starts copying the primary’s data, saves its new role to nodes.conf, and tells the other nodes. A replica that already follows another primary switches to the new one. While the first copy runs, the replica answers commands that read or write data with LOADING.

A primary can become a replica only while it is empty: it must serve no slots and hold no keys (HotKV’s AI feature data counts as keys here). Move its slots away and empty it first.

CLUSTER REPLICATE NO ONE goes the other way. A replica stops following its primary and becomes the primary of a shard of its own, with a new shard ID, no slots and no data: it drops everything it had copied. Give it slots with CLUSTER ADDSLOTS, or move slots to it (see Scaling a cluster), or make it a replica again with CLUSTER REPLICATE node-id. On a primary, NO ONE replies OK and changes nothing.

In a cluster, use CLUSTER REPLICATE to set up replicas; REPLICAOF belongs to non-cluster replication and is refused in cluster mode with ERR REPLICAOF not allowed in cluster mode.

Return value

Simple string OK in RESP2 and RESP3, or one of these errors:

Case	Error
Unknown node ID	ERR Unknown node <node-id>
The node’s own ID	ERR Can't replicate myself
The target is a replica	ERR I can only replicate a master, not a replica.
This node is a primary with slots or keys	ERR To set a master the node must be empty and without assigned slots.
Cluster mode is off	ERR This instance has cluster support disabled

Examples

127.0.0.1:7003> CLUSTER REPLICATE c5bcbe648892246dde31b5d78443297b493afb63
OK
127.0.0.1:7003> ROLE
1) "slave"
2) "127.0.0.1"
3) (integer) 7000
4) "connected"
5) (integer) 105
127.0.0.1:7003> CLUSTER REPLICATE NO ONE
OK
127.0.0.1:7003> ROLE
1) "master"
2) (integer) 123
3) (empty array)

Refused:

127.0.0.1:7000> CLUSTER REPLICATE ba074e3f3b7c3f622d2dc797baacec7229cb94ac
(error) ERR To set a master the node must be empty and without assigned slots.
127.0.0.1:7004> CLUSTER REPLICATE e7217a7e5c27c9b884f9edd0014a7b8c0a8f7056
(error) ERR I can only replicate a master, not a replica.
127.0.0.1:7001> CLUSTER REPLICATE e7217a7e5c27c9b884f9edd0014a7b8c0a8f7056
(error) ERR Can't replicate myself

Compatibility

Same checks, replies and error strings as Redis 7 and Valkey 8. NO ONE is Valkey 9’s form.

See also

CLUSTER FAILOVER, CLUSTER REPLICAS, CLUSTER NODES, CLUSTER RESET, Replicas and failover