OCM High Availability & Disaster Recovery Flashcards

What Oracle technology provides application-level, transparent failover for database connections during a planned or unplanned outage?

Answer: Application Continuity (AC)

Application Continuity replays in-flight transactions on a new database session after a recoverable failure, making the outage transparent to the application without code changes.

In Oracle Data Guard, which protection mode guarantees zero data loss by requiring the standby to acknowledge redo receipt before the primary commits?

Answer: Maximum Protection

Maximum Protection mode requires at least one standby to confirm redo receipt before each primary transaction commits; if no standby is reachable, the primary shuts down.

Which Oracle utility is used to clone a database or create a standby database directly from the primary without prior backups?

Answer: RMAN DUPLICATE … FROM ACTIVE DATABASE

RMAN DUPLICATE … FROM ACTIVE DATABASE streams datafiles directly from the primary (or auxiliary) instance over an Oracle Net connection to build a clone or standby without needing RMAN backups.

What is the role of the Oracle Notification Service (ONS) in a RAC or Data Guard environment?

Answer: Publishing Fast Application Notification (FAN) events to middleware and connection pools about service state changes

ONS propagates FAN events (instance up/down, service relocate) from the cluster to JDBC/OCI connection pools and middleware, enabling rapid connection failover and load balancing.

In Oracle Data Guard Broker, what is the purpose of the DGMGRL command SWITCHOVER TO?

Answer: Performs a planned role transition with no data loss between primary and standby

SWITCHOVER TO performs an orderly, zero-data-loss role reversal where the current primary becomes a standby and the target standby becomes the new primary.

Which Oracle feature automatically extends a tablespace by adding a new datafile or expanding an existing one when space runs out?

Answer: Automatic Extensible Datafiles (AUTOEXTEND ON)

AUTOEXTEND ON configures a datafile to automatically grow by a specified increment (up to MAXSIZE) when the tablespace runs out of free space, preventing allocation failures.