Your Data Guard environment consists of these components and settings:
1. A primary database
2. Two remote physical standby databases
3. The redo transport mode is set to SYNC.
4. Real-time query is enabled for both standby databases.
5. The DB_BLOCK_CHECKING parameter is set to TRUE on both standby databases.
You notice an increase in redo apply lag time on both standby databases.
Which two would you recommend to reduce the redo apply lag on the standby databases?
A.
Increase the size of the buffer cache on the physical standby database instances.
B.
Increase the number of standby redo log files on the standby databases.
C.
Decrease the redo log file size on the primary database.
D.
Lower DB_BLOCK_CHECKING to MEDIUM or LOW on the standby databases.
E.
Increase the size of standby redo log files on the standby databases.
Explanation:
Use Data Guard Redo Apply Best Practices
To improve the Redo Apply rate of a physical standby database (and media recovery):
* Set DB_CACHE_SIZE to a Value Greater than on the Primary Database
* Set DB_BLOCK_CHECKSUM=FULL and DB_BLOCK_CHECKING=MEDIUM or FULL
* Maximize I/O Rates on Standby Redo Logs and Archived Redo Logs
* Assess Recovery Rate
* Assess Database Wait Events
* Tune I/O Operations
* Assess System Resourceshttps://docs.oracle.com/database/121/HABPT/config_dg.htm#HABPT4904
I think that “D” is wrong, they can be “MEDIUM” or “FULL”, not “LOW”
8.3.6 Use Standby Redo Logs and Configure Size Appropriately
You should configure standby redo logs on all primary and standby databases for improved availability and performance.
For each redo log thread (a thread is associated with an OracleRAC database instance), number of Standby Redo Logs = number of Redo Log Groups + 1
The additional standby redo log eliminates the possibility of a standby database waiting on standby redo log. For example, if a primary database has two instances (threads) and each thread has three online log groups, then you should pre-configure 8 standby redo logs on the primary database and each standby database. Furthermore, if the primary or standby databases are not a symmetrical Real Application Cluster (example 8-node primary Oracle RAC cluster compared to 2-node standby Oracle RAC cluster), then the primary and standby databases should still have an equal number of standby redo logs and all threads should be represented.
What do you think about?
A, D
DB_BLOCK_CHECKING parameter is set to TRUE, Default is FULL
https://docs.oracle.com/database/121/REFRN/GUID-23700E5C-6BFC-48C2-9728-EB1F93F95DD6.htm#REFRN10029
Syntax
DB_BLOCK_CHECKING = { FALSE | OFF | LOW | MEDIUM | TRUE | FULL }