Which two are prerequisites for enabling Automatic Block Media Recovery in a Data Guard environment
consisting of a primary database, one physical standby database and one logical standby database?
A.
FLASHBACK DATABASE must be enabled on the physical standby database.
B.
There must be connectivity between the primary and the physical standby database.
C.
FLASHBACK DATABASE must be enabled on the primary database.
D.
The physical standby database must have Real-Time Apply enabled.
E.
The logical standby database must have Real-Time Query enabled.
Explanation:
C: Flashback Database must be enabled on the target database for RMAN to search the flashback logs for
good copies of corrupt blocks. You must have already enabled Flashback Database on the original primary
database before the failover.
D: Block media recovery is a technique for restoring and recovering corrupt data blocks while data files are
online. If only a few blocks are corrupt, then block media recovery may be preferable to data file media
recovery. For automatic block media recovery to work, a physical standby database must be in real-time query
mode, which requires an Oracle Active Data Guard license.References:
https://docs.oracle.com/cd/E11882_01/server.112/e41134/scenarios.htm
https://docs.oracle.com/database/121/BRADV/rcmblock.htm#BRADV89786
Correct Ans: B, D
Automatic Block Media Recovery and RMAN Block Media Recovery are NOT the same.
Automatic Block Media Recovery:
The Automatic Block Repair feature enables block media recovery to use blocks from a physical standby database to perform the recovery without manual intervention. The physical standby database must have real-time query enabled to take advantage of this feature.
When a query is executed on a physical standby database configured with real-time query and a corrupted block is detected, a valid block is retrieved from the primary database.
When a corrupted block is detected during a recovery operation on the standby database, the recovery process will retrieve a valid block from the primary database.
This feature reduces the amount of time that production data cannot be accessed due to block corruption by automatically repairing the corruption as soon as it is detected. Block recovery time is reduced because up-to-date good blocks from a real-time, synchronized physical standby database are used rather than blocks from disk or tape backups or flashback logs.
Automatic Block Repair also enables the automatic repair of corrupt blocks on the physical standby database. Block media recovery is performed by using blocks retrieved from the primary database. Real-time query must be enabled on the physical standby database to take advantage of this feature.
⁃ Real-time query is not the same as real- time apply.
⁃ Real-time apply allows the recovery mechanisms to read from the standby redo logs at the same time that redo is being written to the standby redo logs. In the normal physical standby mode of operation, the database is only at the mount mode and would not allow any queries against user tables, even though real- time apply is enabled. Real-time query with –
Oracle Active Data Guard extends real-time apply by allowing the database to be opened and queries performed against it.
D says: real time apply must be enabled but document says real time query must be enabled.
So, dont you think D is not correct?
I believe D is right
Real time query must require real time apply so I was considering D.
True : B,D
it has nothing to do with flashback nor logical standby databases , leaves only
answers B and D
B,D