Home » Oracle » 1z0-068 » Which three statements are true about Global Resource Management in an Oracle 12c RAC database?
Which three statements are true about Global Resource Management in an Oracle 12c RAC database?
A. Lazy remastering occurs when an instance shuts with SHUTDOWN IMMEDIATE.
B. Object remastering causes all blocks in any instances’ buffer cache from the same object to be mastered in the Global Resource Directory (GRD).
C. When a database instance fails, then some global resource masters lost from the failing instance are remastered among the surviving instances.
D. Lazy remastering instances occurs when an instance shuts with SHUTDOWN TRANSACTIONAL.
E. Global Enqueue resources are recovered after Global Cache Resources after an instance failure.
Correct Answer: BCD
Explanation/Reference:
Explanation:
B: Remastering is the term used that describes the operation whereby a node attempting recovery tries to own or master the resource(s) that were once mastered by another instance prior to the failure. When one instance leaves the cluster, the GRD of that instance needs to be redistributed to the surviving nodes. RAC uses an algorithm called lazy remastering to remaster only a minimal number of resources during a reconfiguration.
D: Using the SHUTDOWN TRANSACTIONAL command with the LOCAL option is useful to shut down a particular Oracle RAC database instance. Transactions on other instances do not block this operation.
C: Recovery from instance failure is automatic, requiring no DBA intervention. In case of instance failure, a surviving instance can read the redo logs of the failed instance.
For example, when using the Oracle Parallel Server, another instance performs instance recovery for the failed instance. In single-instance configurations, Oracle performs crash recovery for a database when the database is restarted, that is, mounted and opened to a new instance. The transition from a mounted state to an open state automatically triggers crash recovery, if necessary.
Incorrect Answers:
A: After a NORMAL or IMMEDIATE shutdown, instance recovery is not required.
References: https://docs.oracle.com/database/121/RACAD/admin.htm#RACAD8910
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