转自：http://blog.sina.com.cn/s/blog_56359cc90101crx2.html
数据库rman restore database 之后，执行recover database的时候，报告ORA-01245错误，详细的错误信息如下:
SQL> recover database until cancel;
ORA-00279: change 575876 generated at 12/01/2009 08:19:49 needed for thread 1
ORA-00289: suggestion :
/oracle/flash_recovery_area/ORCL/archivelog/2009_12_01/o1_mf_1_2_%u_.arc
ORA-00280: change 575876 for thread 1 is in sequence #2
Specify log: {=suggested | filename | AUTO | CANCEL}
auto
ORA-00308: cannot open archived log
'/oracle/flash_recovery_area/ORCL/archivelog/2009_12_01/o1_mf_1_2_%u_.arc'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
ORA-00308: cannot open archived log
'/oracle/flash_recovery_area/ORCL/archivelog/2009_12_01/o1_mf_1_2_%u_.arc'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01245: offline file 2 will be lost if RESETLOGS is done
ORA-01110: data file 2: '/oracle/oradata/orcl/undotbs01.dbf'
检查ORA-01245那一行，发现是datafile 2状态为offline，解决的方法就是首先将datafile 2 online，然后再recover database。
| SQL> |
SQL> alter database datafile 2 online;
Database altered.
SQL> recover database until cancel;
ORA-00279: change 575876 generated at 12/01/2009 08:19:49 needed for thread 1
ORA-00289: suggestion :
/oracle/flash_recovery_area/ORCL/archivelog/2009_12_01/o1_mf_1_2_%u_.arc
ORA-00280: change 575876 for thread 1 is in sequence #2
Specify log: {=suggested | filename | AUTO | CANCEL}
cancel
Media recovery cancelled.
SQL> alter database open resetlogs;
Database altered.