用磁带后改用本地磁盘备份可能出现的问题：

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of delete command at 03/01/2014 09:45:04
RMAN-06091: no channel allocated for maintenance (of an appropriate type)
使用RMAN> report obsolete;可以看到有两种类型的备份数据在结果中。
处理步骤：
1、删除磁盘过期文件：
rman target sys/####@orcl catalog rman/#####@rman
allocate channel for maintenance device type disk;
resync catalog;
delete obsolete device type disk;
DELETE OBSOLETE REDUNDANCY = 3;

2、删除磁带过期文件：
rman target sys/####@orcl catalog rman/#####@rman
allocate channel for maintenance device type 'sbt_tape'
send  'ENV=(SERVER=ORACLE.BACKUP.200,CLIENT=database.localdomain,DATA_VOLUME_POOL=DDBoost,NO_MULTIPLEX=TRUE)';
DELETE OBSOLETE REDUNDANCY = 3;
此处要与原来写在rman备份脚本里的配置相同。
或者
allocate channel for maintenance device type 'sbt_tape' PARMS 'ENV=(OB2BARTYPE=Oracle9i,OB2APPNAME=backup,OB2BARLIST=swt-oracle-full)';