OCP-1Z0-053-V12.02-78题

78.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.

Answer: C

答案解析：

参考：快速增量备份：http://blog.csdn.net/rlhua/article/details/12321679

通过启用块更改跟踪，可执行快速增量备份。块更改跟踪会将有更改的每个块的物理地址写入到一个文件中。需要执行增量备份时，RMAN 可查看块更改跟踪文件，并只备份该文件所引用的块，而无需通过扫描每个块来确定该块自上次备份以来是否发生过更改。

这会加快增量备份的速度。

只有同级之间的增量累积备份才有完全不一样更改过的块。故选C。