Configure a Hidden Replica Set Member
Hidden members are part of a replica set but cannot become primary and are invisible to client applications. Hidden members may vote in elections. For more information on hidden members and their uses, see Hidden Replica Set Members.
settings.chainingAllowed setting allows secondary members to sync from other secondaries, MongoDB by default prefers non-hidden members over hidden members when selecting a sync target. MongoDB will only choose hidden members as a last resort. If you want a secondary to sync from a hidden member, use the
replSetSyncFrom database command to override the default sync target. See the documentation for
replSetSyncFrom before using the command.
The following example hides the secondary member currently at the index
0 in the
members array. To configure a hidden member, use the following sequence of operations in a
mongo shell connected to the primary, specifying the member to configure by its array index in the
After re-configuring the set, this secondary member has a priority of
0 so that it cannot become primary and is hidden. The other members in the set will not advertise the hidden member in the
When updating the replica configuration object, access the replica set members in the
members array with the array index. The array index begins with
0. Do not confuse this index value with the value of the
members[n]._id field in each document in the
rs.reconfig()shell method can force the current primary to step down, which causes an election. When the primary steps down, the
mongodcloses all client connections. While this typically takes 10-20 seconds, try to make these changes during scheduled maintenance periods.
- Avoid reconfiguring replica sets that contain members of different MongoDB versions as validation rules may differ across MongoDB versions.