Reconfiguring when Members are Up

v1.8+

Use the rs.reconfig() helper in the shell. (Run "rs.reconfig" in the shell with no parenthesis to see what it does.)

$ mongo
> // example : give 1st member priority 2
> cfg = rs.conf()
> cfg.members[0].priority = 2
> rs.reconfig(cfg)

Earlier versions (1.6)

You can reconfigure a set from any other language/driver/version using the replSetReconfig command directly.

$ mongo
> // shell v1.6:
> // example : give 1st set member 2 votes
> cfg = rs.conf()
> cfg.members[0].votes = 2
> cfg.version++
> use admin
> db.runCommand( { replSetReconfig : cfg } )

Requirements

You must connect to the admin db of the current primary.
A majority of members of the set must be up.

Notes

You may experience a short downtime period while the set renegotiates master after a reconfiguration. This typically is 10-20 seconds. As always, it is best to do admin work during planned maintenance windows regardless just to be safe.
In certain circumstances, the primary steps down (perhaps transiently) on a reconfiguration. On a step-down, the primary closes sockets from clients to assure the clients know quickly that the server is no longer primary. Thus, your shell session may experience a disconnect on a reconfig command.

Reconfiguring when Members are Up

v1.8+

Earlier versions (1.6)

Requirements

Notes

See Also

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