Data Guard Role Transition Tips Oracle Database Tips by Donald BurlesonDecember 9, 2015

Oracle Data Guard Types of Database Role Transitions

Oracle9i supports two types of role transitions: switchover and failover. The failover transition can be further categorized into graceful failover and forced failover depending on the amount of data lost during the failover operation. The following sections will present these role transitions in detail.

Role Transition Using Switchover

A switchover operation is a smooth transition of a Oracle instance into the primary role and the primary database into a standby role. This is a two-way activity. During a switchover operation, no data is lost; however, the database services may be affected for the period of time that the databases are switching their roles.

Switchover operation is ideal for performing maintenance activities on the original primary database. These maintenance activities cannot include an upgrade of Oracle software because in a Data Guard configuration, the primary and all the standby databases should be running the same Oracle software release.

Role Transition Using Failover

A failover operation is a true disaster recovery operation. Failover to one of the Oracle instance in Data Guard configuration is performed when the original primary database is damaged beyond easy and timely recovery. Contrary to switchover, a failover operation is a one-way operation that transforms the Oracle instance into the primary database.