Identify the scenarios in which the RMAN CROSSCHECR command is useful. (Choose all that apply.)
A.
To check that the obsolete backups are deleted from the repository records and from the disk.
B.
To update the RMAN repository if you delete archived redo logs with operating system commands.
C.
To update outdated information about backups that disappeared from disk or tape or became corrupted and
inaccessible.
D.
To synchronize the actual files on disk or in the media management catalog with the RMAN repository for
which the backup was not taken using RMAN.
Explanation:
Crosscheck are useful because they can do the following: (Link)
Update outdated information about backups that disappeared from disk or tape or became corrupted
Update the repository if you delete archived redo logs or other files with operating system commands
Use the CROSSCHECK command to synchronize the physical reality of backups and copies with their logical
records in the RMAN repository.
The CROSSCHECK command checks only objects marked AVAILABLE or EXPIRED in the repository by
examining the files on disk for DISK channels or by querying the media manager for sbt channels.
Meaning of Crosscheck Status:
EXPIRED
Object is not found either in file system (for DISK) or in the media manager (for sbt). A backup set is EXPIRED
if any backup piece in the set is EXPIRED.
The CROSSCHECK command does not delete the repository records of the files that it does not find, but
updates their repository records to EXPIRED. You can run DELETE EXPIRED to remove the repository records
for expired files and any existing physical files whose status is EXPIRED.
If backups are EXPIRED, then you can re-execute the crosscheck later and determine whether expired
backups are available. This precaution is especially useful when you use RMAN with a media manager. For
example, if some backup pieces or copies were erroneously marked as EXPIRED because the PARMS
channel settings were incorrect, then after ensuring that the files really do exist in the media manager, run the
CROSSCHECK BACKUP command again to restore those files to AVAILABLE status.
AVAILABLE
Object is available for use by RMAN. For a backup set to be AVAILABLE, all backup pieces in the set must
have the status AVAILABLE.