参考文章:http://gaobo424.iteye.com/blog/1344678
关于FRA官方给出的解释:
To free space in the FRA we could do take a backup of the Flash Recovery Area using the command BACKUP RECOVERY AREA.This command will take the backup of all the files in the FRA to tape only. After this the space occupied by the files in the FRA will be marked as reclaimable。
the larger the fast recovery area, the more useful it is. Ideally, the fast recovery area should be large enough for copies of the data files, control files, online redo log files, and archived redo log files needed to recover the database, and also the copies of these backup files that are kept based on the retention policy.
The Flash Recovery Area is a unified storage location for all recovery-related files and activities in an Oracle Database. It includes Control File, Archived Log Files, Flashback Logs, Control File Autobackups, Data Files, and RMAN files.
（1） BACKUP RECOVERY AREA 命令只能备份到磁带上。 在磁盘上备份会报如下错误：
RMAN> BACKUP RECOVERY AREA; 启动 backup 于 12-8月 -10 使用目标数据库控制文件替代恢复目录 分配的通道: ORA_DISK_1 通道 ORA_DISK_1: SID=15 设备类型=DISK 说明与资料档案库中的任何归档日志都不匹配 说明与资料档案库中的任何数据文件副本都不匹配 RMAN-00571: =========================================================== RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS =============== RMAN-00571: =========================================================== RMAN-03002: backup 命令 (在 08/12/2010 13:50:10 上) 失败 RMAN-06603: 必须在磁盘设备上使用 RECOVERY AREA, RECOVERY FILES 或 DB_RECOVERY_FILE_DEST 指定 TO DESTINATION 选项