You have the following requirements in relation to the detection of block corruption for your database instance:
Check for logical self-consistency of data blocks when modified in memory.
Checksums are calculated before and after the block change.
Checks are performed for the lost writes to the physical standby database.
Which method would help you perform the above checks automatically?
A.
Set the DB_SECUREFILE parameter to PERMITTED.
B.
Set the DB_ULTRA_SAFE parameter to DATA_ONLY.
C.
Set the DB_LOCK_CHECKSUM parameter to TYPICAL.
D.
Set the DB_LOST_WRITE_PROTECT parameter to TYPICAL.
Explanation:
Values:
OFF
When any of DB_BLOCK_CHECKING, DB_BLOCK_CHECKSUM, or
DB_LOST_WRITE_PROTECT are explicitly set, no changes are made.
DATA_ONLY
DB_BLOCK_CHECKING will be set to MEDIUM.
DB_LOST_WRITE_PROTECT will be set to TYPICAL.
DB_BLOCK_CHECKSUM will be set to FULL.
DATA_AND_INDEX
DB_BLOCK_CHECKING will be set to FULL.
DB_LOST_WRITE_PROTECT will be set to TYPICAL.
DB_BLOCK_CHECKSUM will be set to FULL.Values:
OFF or FALSE
No block checking is performed for blocks in user tablespaces. However, semantic block
checking for SYSTEM tablespace blocks is always turned on.
LOW
Basic block header checks are performed after block contents change in memory (for
example, after UPDATE or INSERT statements, on-disk reads, or inter-instance block
transfers in Oracle RAC).
MEDIUM
All LOW checks and full semantic checks are performed for all objects except indexes
(whose contents can be reconstructed by a drop+rebuild on encountering a corruption).
FULL or TRUE
All LOW and MEDIUM checks and full semantic checks are performed for all objects.
