题目：
194.What is an obsolete backup set?
A. A backup set that is missing one or more backup set pieces
B. A backup that has exceeded the retention criteria and is no longer needed
C. A backup set that does not include archived redo logs
D. A backup set that can not be recovered due to corruption
E. A backup set superceded by a datafile copy
参考答案 B
解析
题目意思问，obsolete的备份集是怎么回事？
obsolete backup，是指根据备份策略，已经不需要的备份。选择B 。
参考文档：
https://docs.oracle.com/cd/E11882_01/backup.112/e10642/rcmquick.htm#BRADV89363
Deleting Obsolete Backups
The DELETE command removes RMAN backups and copies from disk and tape, updates the status of the files to DELETED in the control file repository, and removes the records from the recovery catalog (if you use a catalog). If you run RMAN interactively, and if you do not specify the NOPROMPT option, then DELETE displays a list of files and prompts for confirmation before deleting any file in the list.
The DELETE OBSOLETE command is particular useful because RMAN deletes backups and data file copies recorded in the RMAN repository that are obsolete, that is, no longer needed. You can use options on the DELETE command to specify what is obsolete or use the configured backup retention policy.
To delete obsolete backups and copies:
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Start RMAN and connect to a target database.
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Run the
DELETE OBSOLETEcommand, as shown in the following example:DELETE OBSOLETE;
See Also:
"Deleting RMAN Backups and Archived Redo Logs" to learn how to use the DELETE command
obsolete backup
A backup that is not needed to satisfy the current backup retention policy. For example, if your retention policy dictates that you must maintain one backup of each data file, but you have two backups of data file 1, then the second backup of data file 1 is considered obsolete.
OBSOLETE obsOperandList
|
Lists full backups, data file copies, and archived redo log files recorded in the RMAN repository that can be deleted because they are no longer needed. See Table 3-6 for description of output. The command works in two steps:
The subclause Note: A backup made with the |
-- 2019-08-24 add
195.What is the purpose of the list expired backup command?
A. Lists all backups impacted by a resetlogs command
B. Lists all backups that are subject to retention criteria
C. Lists all backups that are missing associated physical backup set pieces
D. Lists the status of datafile backup failures due to the use of the duration command
E. Lists backups that cannot be used by the restore command because they have been marked as disabled
参考答案 C
解析
题目意思问，list expired backup这个命令是做什么的？
这个命令是找出在控制文件中注册(或catalog中)的备份集，但是该备份集在磁盘(或磁带)上又不存在。
所以选择 C
参考文档：
https://docs.oracle.com/cd/E11882_01/backup.112/e10642/rcmmaint.htm#BRADV89637
Deleting Expired RMAN Backups and Copies
If you run CROSSCHECK, and if RMAN cannot locate the files, then it updates their records in the RMAN repository to EXPIRED status. You can then use the DELETE EXPIRED command to remove records of expired backups and copies from the RMAN repository.
The DELETE EXPIRED command issues warnings if any files marked as EXPIRED actually exist. In rare cases, the repository can mark a file as EXPIRED even though it exists. For example, a directory containing a file is corrupted at the time of the crosscheck, but is later repaired, or the media manager was not configured properly and reported some backups as not existing when they really existed.
To delete expired repository records:
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If you have not performed a crosscheck recently, then issue a
CROSSCHECKcommand. For example, issue:CROSSCHECK BACKUP;
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Delete the expired backups. For example, issue:
DELETE EXPIRED BACKUP;
expired backup
A backup whose status in the RMAN repository is EXPIRED, which means that the backup was not found. RMAN marks backups and copies as expired when you run a CROSSCHECK command and the files are absent or inaccessible.
crosscheck
A check to determine whether files on disk or in the media management catalog correspond to the data in the RMAN repository. Because the media manager can mark tapes as expired or unusable, and because files can be deleted from disk or otherwise become corrupted, the RMAN repository can contain outdated information about backups. Run the CROSSCHECK command to perform a crosscheck.
-- 关于crosscheck的一些内容
https://docs.oracle.com/cd/E11882_01/backup.112/e10642/rcmmaint.htm#BRADV8171
Crosschecking the RMAN Repository
To ensure that data about backups in the recovery catalog or control file is synchronized with corresponding data on disk or in the media management catalog, perform a crosscheck. The CROSSCHECK command operates only on files that are currently recorded in the RMAN repository.
If you use a fast recovery area, backup retention policy, and archived redo log deletion policy, then you should not need to perform crosschecks very often. If you delete files by means other than RMAN, then you should perform a crosscheck periodically to ensure that the repository data stays current.
About RMAN Crosschecks
Crosschecks update outdated RMAN repository information about backups whose repository records do not match their physical status. For example, if a user removes archived logs from disk with an operating system command, the repository still indicates that the logs are on disk, when in fact they are not.
Figure 12-1 illustrates a crosscheck of a media manager. RMAN queries the RMAN repository for the names and locations of the four backup sets to be checked. RMAN sends this information to the target database server, which queries the media management software about the backups. The media management software then checks its media catalog and reports back to the server that backup set 3 is missing. RMAN updates the status of backup set 3 to EXPIRED in the repository. The record for backup set 3 is deleted once you run DELETE EXPIRED.
Figure 12-1 Crosschecking a Media Manager
Description of "Figure 12-1 Crosschecking a Media Manager"
Crosschecks are useful because they can do the following:
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Update outdated information about backups that disappeared from disk or tape or became corrupted
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Update the repository if you delete archived redo logs or other files with operating system commands
Use the crosscheck feature to check the status of a backup on disk or tape. If the backup is on disk, then CROSSCHECK checks whether the header of the file is valid. If a backup is on tape, then the command checks that the backups exist in the media management software catalog.
Backup pieces and image copies can have the status AVAILABLE, EXPIRED, or UNAVAILABLE. You can view the status of backups by running the RMAN LIST command or by querying V$BACKUP_FILES or recovery catalog views such as RC_DATAFILE_COPY or RC_ARCHIVED_LOG. A crosscheck updates the RMAN repository so that all of these techniques provide accurate information. RMAN updates each backup in the RMAN repository to status EXPIRED if the backup is no longer available. If a new crosscheck determines that an expired backup is available again, then RMAN updates its status to AVAILABLE.
Note:
The CROSSCHECK command does not delete operating system files or remove repository records. You must use the DELETE command for these operations.
You can issue the DELETE EXPIRED command to delete all expired backups. RMAN removes the record for the expired file from the repository. If for some reason the file still exists on the media, then RMAN issues warnings and lists the mismatched objects that cannot be deleted.
EXPIRED |
Displays backup sets, proxy copies, and image copies marked in the repository as EXPIRED, which means they were not found. See Table 2-9, "List of Backup Sets (for data file backup sets)" for a description of the output.
To ensure that |
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