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mongodb / v3.6 / reference / tutorial-replace-replica-set-member.html

Replace a Replica Set Member

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If you need to change the hostname of a replica set member without changing the configuration of that member or the set, you can use the operation outlined in this tutorial. For example if you must re-provision systems or rename hosts, you can use this pattern to minimize the scope of that change.

Operation

To change the hostname for a replica set member modify the members[n].host field. The value of members[n]._id field will not change when you reconfigure the set.

See Replica Set Configuration and rs.reconfig() for more information.

Note

Any replica set configuration change can trigger the current primary to step down, which forces an election. During the election, the current shell session and clients connected to this replica set disconnect, which produces an error even when the operation succeeds.

Example

To change the hostname to mongo2.example.net for the replica set member configured at members[0], issue the following sequence of commands:

cfg = rs.conf()
cfg.members[0].host = "mongo2.example.net"
rs.reconfig(cfg)