053第495題，053495

053第495題，053495
495.Which statement is true regarding the VALIDATE DATABASE command?
A. It checks the database for intrablock corruptions only.
B. It checks for block corruption in the valid backups of the database.
C. It checks the database for both intrablock and interblock corruptions.
D. It checks for only those corrupted blocks that are associated with data files.
Answer: A

For very important databases, you may want to execute additional proactive checks (possibly daily
during low peak interval periods). You can schedule periodic health checks through the Health
Monitor or by using the RMAN VALIDATE command. In general, when a reactive check detects
failure(s) in a database component, you may want to execute a more complete check of the affected
component.
The RMAN VALIDATE DATABASE command is used to invoke health checks for the database and
its components. It extends the existing VALIDATE BACKUPSET command. Any problem detected
during validation is displayed to you. Problems initiate the execution of a failure assessment. If a
failure is detected, it is logged into ADR as a finding. You can use the LIST FAILURE command to
view all failures recorded in the repository.
The VALIDATE command supports validationof individual backup sets and data blocks. In a
physical corruption, the database does not recognize the block at all. In a logical corruption, the
contents of the block are logically inconsistent. By default, the VALIDATE command checks for
physical corruption only. You can specify CHECK LOGICAL to check for logical corruption as well.
Block corruptions can be divided into interblock corruption and intrablock corruption. In intrablock
corruption, the corruption occurs within the block itself and canbe either physical or logical
corruption. In interblock corruption, the corruption occurs between blocks and can be only logical
corruption. The VALIDATE command checks for intrablock corruptions only.

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