系统表空间损坏，启动实例会提示已下错误：数据库只能启动到mount状态。

SQL> startup

ORACLE instance started.

Total System Global Area 1048059904 bytes

Fixed Size                  2235000 bytes

Variable Size             608175496 bytes

Database Buffers          432013312 bytes

Redo Buffers                5636096 bytes

Database mounted.

ORA-01157: cannot identify/lock data file 1 - see DBWR trace file

ORA-01110: data file 1: '/u01/app/oracle/oradata/orcl/system01.dbf'

警告日志提示文件头损坏：

ALTER DATABASE OPEN

Errors in file /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_dbw0_3715.trc:

ORA-01157: cannot identify/lock data file 1 - see DBWR trace file

ORA-01110: data file 1: '/u01/app/oracle/oradata/orcl/system01.dbf'

ORA-27048: skgfifi: file header information is invalid

这里利用数据库之前做好的全备份恢复system01.dbf文件：

回复步骤：

A、      启动实例到mount状态，恢复系统表空间数据文件必须在数据库mount状态下进行。

SQL> startup mount

B、       在RMAN中，执行restore命令还原损坏的系统表空间文件。

RMAN> restore datafile 1;

Starting restore at 02-DEC-12

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=20 device type=DISK

channel ORA_DISK_1: starting datafile backup set restore

channel ORA_DISK_1: specifying datafile(s) to restore from backup set

channel ORA_DISK_1: restoring datafile 00001 to /u01/app/oracle/oradata/orcl/system01.dbf

channel ORA_DISK_1: reading from backup piece /u01/app/oracle/backup/full_ORCL_20121201_6_1.bak

channel ORA_DISK_1: piece handle=/u01/app/oracle/backup/full_ORCL_20121201_6_1.bak tag=TAG20121201T193434

channel ORA_DISK_1: restored backup piece 1

channel ORA_DISK_1: restore complete, elapsed time: 00:00:35

Finished restore at 02-DEC-12

C、       在RMAN中，执行recover datafile 1 利用归档和在线日志恢复数据文件。

RMAN> recover datafile 1;

Starting recover at 02-DEC-12

using channel ORA_DISK_1

starting media recovery

media recovery complete, elapsed time: 00:00:02

Finished recover at 02-DEC-12

D、      打开数据库，恢复完成。

RMAN> alter database open;

database opened

如果数据库在运行过程中发现系统表空间数据文件损坏，要先关闭

实例（shutdown abort），再启动到mount状态下恢复，恢复方法相同。