错误信息如下：
RMAN> backup database tag='full20160112' format '/orabak/rman/full20160112' include current controlfile;
Starting backup at 12-JAN-16
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=1 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00001 name=/oradata/rmandb/system01.dbf
input datafile file number=00002 name=/oradata/rmandb/sysaux01.dbf
input datafile file number=00005 name=/oradata/rmandb/example01.dbf
input datafile file number=00003 name=/oradata/rmandb/undotbs01.dbf
input datafile file number=00004 name=/oradata/rmandb/users01.dbf
channel ORA_DISK_1: starting piece 1 at 12-JAN-16
channel ORA_DISK_1: finished piece 1 at 12-JAN-16
piece handle=/orabak/rman/full20160112 tag=FULL20160112 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:01:06
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 12-JAN-16
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on ORA_DISK_1 channel at 01/12/2016 20:55:59
ORA-19504: failed to create file "/orabak/rman/full20160112"
ORA-27038: created file already exists
Additional information: 1
RMAN>
分析：
ORA-27038: 创建文件时发现文件已经存在。这是因为RMAN在创建备份集的时候，默认是写入多个备份集、多个备份片中的，如果名字固定，下次创建将还是同样的名字。将名字改为符号即可。
RMAN> backup database tag='full20160112_rmandb' format '/orabak/rman/full_%d_%T_%s_%p' include current controlfile;
Starting backup at 12-JAN-16
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00001 name=/oradata/rmandb/system01.dbf
input datafile file number=00002 name=/oradata/rmandb/sysaux01.dbf
input datafile file number=00005 name=/oradata/rmandb/example01.dbf
input datafile file number=00003 name=/oradata/rmandb/undotbs01.dbf
input datafile file number=00004 name=/oradata/rmandb/users01.dbf
channel ORA_DISK_1: starting piece 1 at 12-JAN-16
channel ORA_DISK_1: finished piece 1 at 12-JAN-16
piece handle=/orabak/rman/full_RMANDB_20160112_4_1 tag=FULL20160112_RMANDB comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:01:15
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
channel ORA_DISK_1: starting piece 1 at 12-JAN-16
channel ORA_DISK_1: finished piece 1 at 12-JAN-16
piece handle=/orabak/rman/full_RMANDB_20160112_5_1 tag=FULL20160112_RMANDB comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 12-JAN-16
Starting Control File and SPFILE Autobackup at 12-JAN-16
piece handle=/u01/app/oracle/product/11.2.0/db_1/dbs/c-3689252377-20160112-00 comment=NONE
Finished Control File and SPFILE Autobackup at 12-JAN-16