本文探讨了RMAN在进行0级和1级增量备份时如何使用块变更跟踪文件。详细解释了在首次0级备份中由于变更跟踪文件不包含变更块信息，RMAN需要扫描整个数据文件；而在1级增量备份中，则利用该文件确定自上次0级备份以来变更的块。
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You enable block change tracking. You issue the following command:
BACKUP INCREMENTAL LEVEL 0 DATABASE;
The next day, you issue the following command:
BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE;
Which statement about the use of the change tracking file is true?
A. RMAN reads the block change tracking file only when it performs the incremental level 0 backup.
B. RMAN reads the block change tracking file when it performs both incremental backups.
C. RMAN reads the block change tracking file only when it performs the incremental level 1 backup.
Section: (none)
Explanation
Explanation/Reference:
Explanation:
RMAN reads the block change tracking file only when it performs the incremental level 1 backup. After you
enable block change tracking, you perform a level 0 incremental backup. For this backup, RMAN has to
scan the entire datafile because the change tracking file does not contain information about the changed
blocks.
Next, you perform an incremental level 1 backup. For this backup, RMAN uses the block change tracking
file to determine the blocks that have changed since the incremental level 0 backup.
The option that states RMAN reads the block change tracking file only when it performs the incremental
level 0 backup is incorrect. For the first incremental level 0 backup, the change tracking file does not
contain information about the changed blocks, and RMAN has to scan the entire datafiles to determine the
blocks that have changed.
The option that states RMAN reads the block change tracking file when it performs both incremental
backups is incorrect. RMAN only uses the block change tracking file for the incremental level 1 backup.
The option that states RMAN does not read the block change tracking file when it performs either
incremental backup is incorrect. RMAN uses the block change tracking file for the incremental level 1
backup, but not for the incremental level 0 backup.
You enable block change tracking. You issue the following command:
BACKUP INCREMENTAL LEVEL 0 DATABASE;
The next day, you issue the following command:
BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE;
Which statement about the use of the change tracking file is true?
A. RMAN reads the block change tracking file only when it performs the incremental level 0 backup.
B. RMAN reads the block change tracking file when it performs both incremental backups.
C. RMAN reads the block change tracking file only when it performs the incremental level 1 backup.
D. RMAN does not read the block change tracking file when it performs either incremental backup.
Section: (none)
Explanation
Explanation/Reference:
Explanation:
RMAN reads the block change tracking file only when it performs the incremental level 1 backup. After you
enable block change tracking, you perform a level 0 incremental backup. For this backup, RMAN has to
scan the entire datafile because the change tracking file does not contain information about the changed
blocks.
Next, you perform an incremental level 1 backup. For this backup, RMAN uses the block change tracking
file to determine the blocks that have changed since the incremental level 0 backup.
The option that states RMAN reads the block change tracking file only when it performs the incremental
level 0 backup is incorrect. For the first incremental level 0 backup, the change tracking file does not
contain information about the changed blocks, and RMAN has to scan the entire datafiles to determine the
blocks that have changed.
The option that states RMAN reads the block change tracking file when it performs both incremental
backups is incorrect. RMAN only uses the block change tracking file for the incremental level 1 backup.
The option that states RMAN does not read the block change tracking file when it performs either
incremental backup is incorrect. RMAN uses the block change tracking file for the incremental level 1
backup, but not for the incremental level 0 backup.
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