The sh.addShard() method has the following parameter:
Parameter Type Description host string The hostname of either a standalone database instance or of a replica set. Include the port number if the instance is running on a non-standard port. Include the replica set name if the instance is a replica set, as explained below.
The sh.addShard() method has the following prototype form:
The host parameter can be in any of the following forms:
[hostname] [hostname]:[port] [replica-set-name]/[hostname] [replica-set-name]/[hostname]:port
When you add a shard to a sharded cluster, you affect the balance of chunks among the shards of a cluster for all existing sharded collections. The balancer will begin migrating chunks so that the cluster will achieve balance. See Sharded Collection Balancing for more information.
Changed in version 2.6: Chunk migrations can have an impact on disk space. Starting in MongoDB 2.6, the source shard automatically archives the migrated documents by default. For details, see moveChunk directory.
To add a shard on a replica set, specify the name of the replica set and the hostname of at least one member of the replica set, as a seed. If you specify additional hostnames, all must be members of the same replica set.
The following example adds a replica set named repl0 and specifies one member of the replica set: