===基础知识补充
RMAN> CONFIGURE RETENTION POLICY TO REDUNDANCY 3; ---配置保留策略，冗余3份
RMAN> crosscheck backup; ---检查备份集
RMAN> delete noprompt expired backup; ---删除过期备份集（磁盘或磁带上备份集被手动删除）
RMAN> crosscheck copy; ---检查备份集的copy或归档日志文件
RMAN> delete noprompt expired copy; ---删除过期备份集的copy或归档日志文件
RMAN> delete noprompt obsolete; ---删除过时的备份集（和保留策略相关）
===现象：RMAN删除过时备份，报错ORA-19606
RMAN> delete obsolete;
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of delete command on ORA_DISK_1 channel at 09/02/2019 08:00:44
ORA-19606: Cannot copy or restore to snapshot control file
===解决办法：重建 snapshot controlfile文件
RMAN> configure snapshot controlfile name TO '/u01/app/oracle/product/11.2.0/dbs/snapcf_aps.f_bak'; ---重命名SNAPSHOT控制文件
RMAN> crosscheck controlfilecopy '/u01/app/oracle/product/11.2.0/dbs/snapcf_aps.f'; ---crosscheck controlfilecopy快照控制文件
RMAN> delete expired controlfilecopy '/u01/app/oracle/product/11.2.0/dbs/snapcf_aps.f'; ---删除过期controlfilecopy快照控制文件
RMAN> configure snapshot controlfile name to /u01/app/oracle/product/11.2.0/dbs/snapcf_aps.f'; ---重新配置快照控制文件
RMAN> configure snapshot controlfile name clear; ---配置默认快照控制文件
至此，就可以再执行上面的删除命令了。