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
https://docs.oracle.com/database/121/BRADV/rcmblock.htm#BRADV89785
Prerequisites for Block Media Recovery
The following prerequisites apply to the RECOVER … BLOCK command:
Flashback Database must be enabled on the target database for RMAN to search the flashback logs for good copies of corrupt blocks.
The target database must be associated with a real-time query physical standby database for RMAN to search the database for good copies of corrupt blocks.
so A, D
A,E (real time query instead of real time apply)
E is also impossible (logical standby)
A/C depending on the target (where the block corruption occurs)
The target database must be associated with a real-time query physical standby database for RMAN to search the database for good copies of corrupt blocks.
as the standby does not have a rtq physical associated, c is the better choice?
Why not B? Will logical standby send the right block?
a logical standby can never send a block, as the physical structure (blocks) are not the same between a primary and a logical stdby
AD is correct.
E: impossible (logical standby for block recovery)
D: incorrect (realtime QUERY instead of realtime APPLY needs to be enabled)
RTQ in Logical Standby???
Correct Answers: A,D
http://oradb-srv.wlv.ac.uk/E50529_01/SBYDB/manage_ps.htm#SBYDB00707
10.2.1.5 Automatic Block Media Recovery
If corrupt data blocks are encountered when a database is accessed, they can be automatically replaced with uncorrupted copies of those blocks. This requires the following conditions:
•The physical standby database must be operating in real-time query mode, which requires an Oracle Active Data Guard license.
•The physical standby database must be running real-time apply.
Automatic block media recovery works in two directions depending on whether the corrupted blocks are encountered on the primary or on the standby.
According documentation of Data Guard D and E is correct.
B, D
Correct
B:
Corrupted Blocks On the Primary
(…) the primary automatically searches for good copies of those blocks on a standby and, if they are found, has them shipped back to the primary.
(…) the primary requires a LOG_ARCHIVE_DEST_n to the standby only (a physical standby, a cascading physical standby, or a far sync instance)
Corrupted Blocks On a Standby
(…) the standby automatically initiates communication with the primary and requests uncorrupted copies of those blocks
. The LOG_ARCHIVE_CONFIG parameter is configured with a DG_CONFIG list and a LOG_ARCHIVE_DEST_n parameter is configured for the primary database.
or
. The FAL_SERVER parameter is configured and its value contains an Oracle Net service name for the primary database.
D:
If corrupt data blocks are encountered when a database is accessed, they can be automatically replaced with uncorrupted copies of those blocks. This requires the following conditions:
The physical standby database must be operating in real-time query mode, which requires an Oracle Active Data Guard license.
The physical standby database must be running real-time apply.
Reference:
https://docs.oracle.com/database/121/SBYDB/manage_ps.htm#SBYDB00700
Incorrect:
A, C:
Prerequisites for Block Media Recovery
The following prerequisites apply to the RECOVER … BLOCK command:
(…)
Flashback Database must be enabled on the target database for RMAN to search the flashback logs for good copies of corrupt blocks.
Note: This is without Data Guard, and is using “RECOVER … BLOCK”
Reference: https://docs.oracle.com/database/121/BRADV/rcmblock.htm#BRADV89785
E:
Real-Time Query can only be done on a Physical Standby database
B,D
If corrupt data blocks are encountered when a database is accessed, they can be automatically replaced with uncorrupted copies of those blocks. This requires the following conditions:
The physical standby database must be operating in real-time query mode, which requires an Oracle Active Data Guard license.
The physical standby database must be running real-time apply.
Automatic block media recovery works in two directions depending on whether the corrupted blocks are encountered on the primary or on the standby.
I believe B & D
B and D !!
It’s correct that database blocks can be recovered automatically from flashback logs but the first search source is a Physical Standby.