早上检查测试环境中的备份发现备份成功但有错误，rman日志如下：
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Starting Control File and SPFILE Autobackup at 08-JUN-16
piece handle=+FRADG/db/autobackup/2016_06_08/s_913946012.2577.913946015 comment=NONE
Finished Control File and SPFILE Autobackup at 08-JUN-16
ORA-00245: control file backup operation failed

RMAN-08132: WARNING: cannot update recovery area reclaimable file list

released channel: c1

released channel: c2

RMAN retention policy will be applied to the command
RMAN retention policy is set to redundancy 1
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=1158 instance=db2 device type=DISK
Deleting the following obsolete backups and copies:
Type                 Key    Completion Time    Filename/Handle
-------------------- ------ ------------------ --------------------
Backup Set           3041   07-JUN-16
  Backup Piece       3042   07-JUN-16          /ora_backup/db/aur7giep_1_1
Backup Set           3040   07-JUN-16
  Backup Piece       3041   07-JUN-16          /ora_backup/db/avr7giep_1_1
Backup Set           3042   07-JUN-16
  Backup Piece       3043   07-JUN-16          +FRADG/db/autobackup/2016_06_07/s_913859436.2205.913859439
deleted backup piece
backup piece handle=/ora_backup/db/aur7giep_1_1 RECID=3042 STAMP=913852889
deleted backup piece
backup piece handle=/ora_backup/db/avr7giep_1_1 RECID=3041 STAMP=913852890
deleted backup piece
backup piece handle=+FRADG/db/autobackup/2016_06_07/s_913859436.2205.913859439 RECID=3043 STAMP=913859438
Deleted 3 objects

ORA-00245: control file backup operation failed

RMAN-08132: WARNING: cannot update recovery area reclaimable file list


--------------------------
同时在alert文件中发现如下错误

Wed Jun 08 01:54:27 2016
Errors in file /u01/app/oracle/diag/rdbms/db/db2/trace/db2_ora_19293.trc:
ORA-00245: control file backup operation failed

11.2.0.2的oerr ora
00245, 00000, "control file backup operation failed"
// *Cause:  Failed to create a control file backup because some process
//          signaled an error during backup creation.
// *Action: Check alert files for further information. This usually happens
//          because some process could not access the backup file during
//          backup creation. Any process of any instance that starts a read/write
//          control file transaction must have an access to the backup control file
//          during backup creation.

11.2.0.3的oerr ora
00245, 00000, "control file backup failed; target is likely on a local file system"
// *Cause:  Failed to create a control file backup because some process
//          signaled an error during backup creation. This is likely caused
//          by the backup target being on a local file system so it could not
//          be accessed by other instances. It can also be caused by other
//          I/O errors to the backup target. Any process of any instance that
//          starts a read/write control file transaction must have access
//          to the backup control file during backup creation.
// *Action: Check alert files of all instances for further information.

网上查了下，发现惜分飞的一篇博客是一样的，http://www.xifenfei.com/2012/03/rman-%E5%A4%87%E4%BB%BD%E5%87%BA%E7%8E%B0ora-00245rman-08132.html
确实控制文件在+FRADG上的备份是已经完成了，但是后面这个控制文件备份失败，原因是控制文件的快照备份失败
查看一下rman的配置参数，控制文件的快照备份是在本地的，但是这是一个使用ASM的RAC
RMAN> show all;

using target database control file instead of recovery catalog
RMAN configuration parameters for database with db_unique_name DB are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1;
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP ON;
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
......
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u01/app/oracle/product/11.2.0/dbhome_1/dbs/snapcf_db2.f'; # default

然后到MOS上查了一下，发现这个已经找不到： RAC BACKUP FAILS WITH ORA-00245: CONTROL FILE BACKUP OPERATION FAILED [ID 1268725.1]

而替代的是 Bug 17964981 : BACKUP CONTROLFILE WITH RMAN SOMETINES RETURNS ORA-245

在11.2.0.3已经修复了，嗯，确实这个测试环境是11.2.0.2的，而其他的一个测试环境11.2.0.3，RAC的rman配置参数默认下控制文件快照备份还是放到了本地目录下而没有放到共享存储下的
而其他的生产环境，无论11.2.0.3或者11.2.0.4都是放到了共享存储下的
那安全起见，还是都把RAC的这个快照备份放到共享存储下吧
RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/snapcf_.f';