（52）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.

答案：（B）

解析：

该参数设置其它参数的默认值来控制保护的级别

DB_ULTRA_SAFE = {OFF | DATA_ONLY | DATA_AND_INDEX}

1. OFF,当DB_BLOCK_CHECKING, DB_BLOCK_CHECKSUM, DB_LOST_WRITE_PROTECT任何一个被显示设置时,不会有任何改变.

2. DATA_ONLY

    DB_BLOCK_CHECKING = MEDIUM

    DB_BLOCK_CHECKSUM = FULL

    DB_LOST_WRITE_PROTECT = TYPICAL

3. DATA_AND_INDEX

    DB_BLOCK_CHECING = FULL

    DB_BLOCK_CHECKSUM = FULL

    DB_LOST_WRITE_PROTECT = TYPICAL