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70. You configured the Flash Recovery Area (FRA) for your database. The database instance is running

in ARCHIVELOG mode. The default location for the archived redo log files is the Flash Recovery Area.

Which two files are removed automatically if the space is required in the FRA as per the retention policy?

(Choose two.)

A.flashback log files 

B.backups that have become obsolete 

C.copies of the data files and control files 

D.archived redo log files that have multiple copies in a different archive location and not backed up

Answer: AB  

答案解析：

參考：http://docs.oracle.com/cd/E11882_01/server.112/e10897/backrest.htm#ADMQS12218

分配給快速恢復區的磁碟空間量取決於資料庫的大小和活動級別。通常情況下，快速恢復

區越大，就越有用。理想情況下，快速恢復區應足夠大，可存放資料檔案和控制檔案副本，

以及基於保留策略從保留的備份恢復資料庫所需的閃回日誌、聯機重做日誌和歸檔日誌。

（簡而言之，快速恢復區至少應為資料庫大小的兩倍，以便可保留一個備份和若干歸檔

日誌。）

快速恢復區的空間管理由備份保留策略控制。保留策略確定檔案何時過時，即何時這些文

件對達到資料恢復目標已不再有用。Oracle DB 通過刪除不再需要的檔案自動管理該儲存。

About the Backup Retention Policy and the Fast Recovery Area

Space management in the fast recovery area is governed by a backup retention policy. A retention policy determines when files are obsolete, meaning that they are no longer needed to meet your data recovery objectives.

Retention policies can be based on redundancy of backups or on a recovery window (period of time). When using a policy based on redundancy, the fast recovery area considers a backup of a file obsolete only when the RMAN repository has records of a specified number of more recent backups of that file. When using a recovery policy based on a period of time (or window), you specify a time interval in days. Files are obsolete only when they are no longer needed for complete recovery or point-in-time recovery to a system change number (SCN) within the window. Therefore, a recovery retention policy based on a window is recommended.

Even after files in the fast recovery area are obsolete, they are typically not deleted until space is needed for new files. If space permits, files recently moved to tape remain on disk to avoid restoring them from tape for a recovery. The automatic deletion of obsolete files and files moved to tape from the fast recovery area makes it a convenient archiving destination. Other destinations require manual deletion of logs.

1. Select Enable Flashback Database.

   This option specifies that the database should generate flashback logs in the fast recovery area, enabling you to use Flashback Database. During usual operation, the database occasionally logs images of data blocks to the flashback logs. The database automatically creates, deletes, and resizes flashback logs.

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