All datasources within a dataservice have a specific role within he
dataservice. The master role is
one that provides a source of replication information, and a slave one
that receives that information.
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 slave
and included in load-balanced operations.
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.