n is either primary, backup, or auto.
ShardMirrorMember configures mirrored cluster nodes by assigning failover roles to individual nodes. In conjunction with several other parameters, ShardMirrorMember can be used to deploy a mirrored sharded cluster. For a description of this process, see Configure or Deploy a Mirrored Cluster Using CPF Settings in the “Horizontally Scaling for Data Volume with Sharding” chapter in the Scalability Guide.
The value specified for ShardMirrorMember determines the failover role of the instance as follows:
primary — The instance is configured or deployed as the primary of a data node mirror. If ShardRole is set to NODE1, it becomes the primary of the node 1 mirror; if set to DATA, it becomes the primary of a data node other than node 1.
backup — The instance is configured or deployed as the backup to the primary identified by ShardClusterURL.
auto — The instance’s mirror failover role is based on the hostnames of the nodes on which the instances are deployed: if the integer following the final hyphen (-) in the hostname is even, the instance is configured as a primary, and if odd, as a backup. The instance on the host with a name matching the regular expression specified for ShardMasterRegexp is configured or deployed as the node 1 primary and the remaining nodes are configured or deployed according to the hostname pattern.
ArbiterURL to specify the address of the arbiter for a mirrored sharded cluster.
ShardRole to specify the sharded cluster role of the instance.
ShardClusterURL to specify the node to use as a template when adding an instance to a sharded cluster.
ShardMirrorMember to specify the failover role of a data node in a mirrored sharded cluster.
ShardMasterRegexp to identify the sharded cluster node to be configured as data node 1 based on hostname.
ShardRegexp to identify the nodes to be configured as sharded cluster data nodes (other than data node 1) based on hostname.