052-81

You are managing an Oracle Database 11g database with this backup strategy:
- Every Sunday night, level 0 backup is performed.
- On Monday night and subsequent days, level 1 incremental backup is performed.
The backups are not cumulative incremental. Which statement about Monday's backup is true?
A.The backup contains all the used blocks.
B.The backup contains all the used and unused blocks.
C.The backup contains blocks that have changed since the last level 0 backup.
D.The backup contains blocks that have changed since the last level 1 backup taken last week.

这里如果是非周日和周一的1级累积备份也会和C选项一样

差异备份
差异备份是RMAN生成增量备份的默认类型。
差异备份是指备份自上一次同级别或低级别差异增量备份以来所有发生变化了的数据块。
backup incremental level 1 database;

累积备份
累积备份是指备份自上次0级备份以来所有发生变化的数据块，忽略之前的1级备份。
backup incremental level 1 cumulative database;

假设周一做了0级增量备份，周二做了1级差异备份，周三仍做了1级差异备份，那么，周二做的备份中包含自周一0级备份以来所有的变化数据。周三的备份则包含了自周二1级差异备份以来的所有的变化数据。

假设周一做了0级增量备份，周二做了1级累积备份，周三仍做了1级累积备份，那么，周二做的备份中包含自周一0级备份以来所有的变化数据。周三的备份则包含了自周一0级增量备份以来的所有的变化数据。