5.3.3. Understanding Datasource Roles

All datasources within a dataservice have a specific role within he dataservice. The Primary role is one that provides a source of replication information, and a Replica one that receives that information.

Role Supplies Replication Data Receives Replication Data Load Balancing Failover
Master Yes No Yes Yes
Slave No Yes Yes Yes
Standby No Yes No Yes
Archive No Yes Yes No

More detailed information for each role:

  • master

    A datasource in a Primary role is providing a source for replication information to other datasources in the dataservice and is able to provide both read and write connections for applications.

  • slave

    A Replica datasource is receiving data from a Primary and having that replicated data applied by Tungsten Cluster. Replicas are used for read-only operations by applications.

  • standby

    A standby datasource receives replication data, but is never chosen by the connector to act as a read source by application clients. Standby datasources are therefore kept up to date with replication, but not used for load balancing.

    When a failover occurs, a standby datasource can be enabled as a standard Replica and included in load-balanced operations.

  • archive

    An archive datasource can be used to provide an active (up to date) copy of the data, without the datasource being used in the event of a failover. This can be useful for providing backup support, offline querying outside of the normal dataservice operations, or auditing purposes.