备份脚本没什么大问题，保留备份集可以用如下配置，1代表保留一份：

CONFIGURE RETENTION POLICY TO REDUNDANCY = 1;

另外备份数据库在一个节点上执行备份就可以。看到的多个备份文件，是备份片，您开了4个channel来备份。

检查备份可以登录rman 命令窗口执行：

rman target /

list backup;

或者

list backup of database;

后缀1和2大小一样，是不是对应节点呢？

你这个很可能是1、2实例同时执行了备份任务导致：

参考

Database Backup and Recovery Reference 

 formatSpec的说明

%T Specifies the year, month, and day in the Gregorian calendar in this format: YYYYMMDD.

%s Specifies the backup set number. This number is a counter in the control file that is

incremented for each backup set. The counter value starts at 1 and is unique for the lifetime of

the control file. If you restore a backup control file, then duplicate values can result. Also,

CREATE CONTROLFILE initializes the counter back to 1.

%p Specifies the piece number within the backup set. This value starts at 1 for each backup set

and is incremented by 1 as each backup piece is created.

%c Specifies the copy number of the backup piece within a set of duplexed backup pieces. If you

did not duplex a backup, then this variable is 1 for backup sets and 0 for proxy copies. If a

command is enabled, then the variable shows the copy number. The maximum value for %c is

256.

 明 白谢谢 我ASM配置成
normal   有没有办法修改成external 呢

没有办法，只有重建磁盘组。

 那是不是要重新安装了呀

如果没有给ocr和voting disk单独划盘就重装吧。存储也重新规划好

 RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on c1 channel at 02/28/2019 09:25:45
RMAN-20039: format requires %c when duplexing

----备份脚本

run{      

allocate channel c1 device type disk;
allocate channel c2 device type disk;
allocate channel c3 device type disk;
allocate channel c4 device type disk;
crosscheck backup;
sql 'alter system archive log current';
backup spfile format '/bak/backup/spfile_%T_%s_%p_%c';
#backup database format '/bak/backup/dbbk_0_%d_%t_%u_%s_%p';
backup as compressed backupset incremental level 0 database format '/bak/backup/dbbk_0_%d_%t_%u_%s_%p';
sql 'alter system archive log current';
backup archivelog all format '/bak/backup/arc_%T_%s_%p_%c' delete all input;
backup current controlfile format '/bak/backup/cntrl_%T_%s_%p_%c';
crosscheck archivelog all;
delete noprompt expired backup;
delete noprompt obsolete;
delete noprompt backup of database completed before 'sysdate - 7';
release channel c1;
release channel c2;
release channel c3;
release channel c4;

}

备份数据文件不加%C就会报错，加%C有两份一样的

如果设置不冗余就可以不需要加c%，否则就会出现你的报错。

CONFIGURE RETENTION POLICY TO REDUNDANCY = 1;
show all