Dataguard Protection Modes

Dataguard Protection Modes

Data Guard operates in three different protection modes:

Maximum Performance
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Default protection mode with the primary concern on the performance. In this mode, transaction commits as soon as redo data written to the local redo logs. It provides less data protection compared to other modes.

Maximum Availability
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Highest level of data protection while the primary database is available. Transaction commits, when redo written to the local redo logs and at least one standby location. In case of no standby location is available, the primary doesn’t shut down and continue to generate redo entries.

Maximum Protection
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No (Zero) data loss. Redo entries must be written to the local online redo logs and at least one standby location before a transaction commits on primary. Primary will shut down if it can’t write redo to the standby database.

Some terminology
Switch-over
Switch-over is planned role changes between primary and standby databases usually to allow maintenance activities to be performed on primary.

Fail-over
On the other hand, Fail-over occurs in the event of taking the primary database offline (can be because of unplanned failure). In this case one of the standbys becomes new primary and original primary may need to be rebuilt.

The main difference between switchover and failover is primary database is still available in the case of switchover.