OCP-1Z0-053-V12.02-10题

10.Consider the following scenario for your database:

-Backup optimization is enabled in RMAN. The recovery window is set to 7 days in RMAN. The most

recent backup to disk for the TOOLS tablespace was taken on November 3, 2007.

The TOOLS tablespace is read-only since November 4, 2007.

On November 23, 2007, you issue the RMAN command to back up the database to disk. Which statement

is true regarding the backup of the TOOLS tablespace?

A. The RMAN backup fails because the TOOLS tablespace is read-only

B. The RMAN skips the backup of the tablespace because backup optimization is enabled

C. The RMAN makes backup because optimization can be enabled only for backups to disk

D. The RMAN makes the backup because no backup of the tablespace exists within the seven day window

Answer: D

答案解析：

参考：备份优化：http://blog.csdn.net/rlhua/article/details/12312463

备份优化是指：通过跳过未更改的文件（如已经备份的只读和脱机数据文件）优化整个数据库备份。

启用了备份优化：RMAN> CONFIGURE BACKUP OPTIMIZATION ON;

参考：指定保留策略: http://blog.csdn.net/rlhua/article/details/12308231

保留恢复到指定天数内任意时间的状态所需的备份（时间点恢复）

可以使用下列命令语法配置恢复窗口保留策略：

RMAN> CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF <天数>DAYS;

本题设置为7天。

RMAN> CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7 DAYS;

题意：最近的一次TOOLS表空间是 November 3, 2007，November 4, 2007变为只读，November 23, 2007执行RMAN备份。

仅当符合保留策略的备份不存在时，备份优化才会让RMAN 备份只读表空间。

根据备份优化，如果在November 3, 2007之后的7天内备份，则在rman备份时跳过只读表空间，即TOOLS表空间。

如果超过7天，即之前保留的备份已经没有了，再次执行RMAN命令时，此时的TOOLS表空间并没有备份，则执行RMAN命令时，TOOLS表空间也要被备份。

故选D。tools这个只读表空间在7天的时间窗口没有备份。