2节点日志中出现如下错误：
ORA-00245: control file backup failed; in Oracle RAC, target might not be on shared storage

2.问题分析
[oracle@db1 ~]$ oerr ora 245
00245, 00000, "control file backup failed; in Oracle RAC, target might not be on shared storage"
// *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 (i.e., RMAN snapshot controlfile) 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 whether RMAN snapshot controlfile is on shared storage.
//          Also, check alert files of all instances for further information.
==>上述提到了snapshot controlfile是在本地文件系统上，其他实例无法获取。要求检查rman配置中 snapshot controlfile是否放在共享存储上。

3.解决方法
1，2节点通过进入rman,通过show all；命令发现2个节snapshot control file都配置在了本地文件系统上。
执行以下命令将snapshot control file配置到共享存储上：
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '+DATA_CDB/cdb/snapcf_cdb.f’;