1、 SYSTEM表空间数据文件丢失恢复
注意：以下的所有实验，都是基于上面的全库备份来做的恢复。
3.1 删除system表空间的所有数据文件。
[oracle@wwldb WWL]$ exit
3.2 再次启动数据库报错。
SQL> startup force
ORACLE instance started.
Total System GlobalArea 285212672 bytes
Fixed Size 1218968 bytes
Variable Size 104859240 bytes
Database Buffers 171966464 bytes
Redo Buffers 7168000 bytes
Database mounted.
ORA-01157: cannotidentify/lock data file 1 - see DBWR trace file
ORA-01110: data file 1:'/DBData/WWL/system01.dbf'
3.3 检查跟踪文件，分析错误。
Errors in file /DBSoft/admin/WWL/bdump/wwl_dbw0_4600.trc:
ORA-01157: Message 1157 not found; No message file for product=RDBMS,facility=ORA; arguments: [1]
ORA-01110: Message 1110 not found; No message file for product=RDBMS,facility=ORA; arguments: [1] [/DBData/WWL/system01.dbf]
ORA-27037: Message 27037 not found; No message file for product=RDBMS,facility=ORA
Linux Error: 2: No such file or directory
Additional information: 3
ORA-1157 signalled during: ALTER DATABASE OPEN...
由如上日志文件我们得出是由于/DBData/WWL/system01.dbf文件丢失，而且这个文件同时又是system表空间的的数据文件，因为system表空间存放了数据字典信息，所以该数据文件是不可以采用脱机的方式实现在线的的恢复。
3.4恢复system表空间数据文件
开始执行恢复分为五个步骤
1、强制启动数据库到mount状态
SQL> startup force mount;
ORACLE instance started.
Total System Global Area 285212672 bytes
Fixed Size 1218968 bytes
Variable Size 104859240 bytes
Database Buffers 171966464 bytes
Redo Buffers 7168000 bytes
Database mounted.
SQL>
2、Restore出来system表空间的数据文件
RMAN> restore datafile 1;
Starting restore at 22-JUN-12
using target database control file instead of recoverycatalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=156 devtype=DISK
channel ORA_DISK_1: starting datafile backupsetrestore
channel ORA_DISK_1: specifying datafile(s) to restorefrom backup set
restoring datafile 00001 to /DBData/WWL/system01.dbf
channel ORA_DISK_1: reading from backup piece/DBBak/bak_WWL_06_22_0vne4ph6_1_1
channel ORA_DISK_1: restored backup piece 1
piece handle=/DBBak/bak_WWL_06_22_0vne4ph6_1_1tag=TAG20120622T010021
channel ORA_DISK_1: restore complete, elapsed time:00:01:06
Finished restore at 22-JUN-12
3、执行system表空间数据恢复。
RMAN> recover datafile 1;
Starting recover at 22-JUN-12
using channel ORA_DISK_1
starting media recovery
archive log thread 1 sequence 20 is already on diskas file/DBData/flash_recovery_area/WWL/archivelog/2012_06_22/o1_mf_1_20_7y804kwr_.arc
archive log thread 1 sequence 21 is already on diskas file/DBData/flash_recovery_area/WWL/archivelog/2012_06_22/o1_mf_1_21_7y80zjqx_.arc
archive log thread 1 sequence 22 is already on diskas file /DBData/flash_recovery_area/WWL/archivelog/2012_06_22/o1_mf_1_22_7y8y7l70_.arc
archive log thread 1 sequence 23 is already on diskas file/DBData/flash_recovery_area/WWL/archivelog/2012_06_22/o1_mf_1_23_7y903v17_.arc
archive logfilename=/DBData/flash_recovery_area/WWL/archivelog/2012_06_22/o1_mf_1_20_7y804kwr_.arcthread=1 sequence=20
archive logfilename=/DBData/flash_recovery_area/WWL/archivelog/2012_06_22/o1_mf_1_21_7y80zjqx_.arcthread=1 sequence=21
media recovery complete, elapsed time: 00:00:02
Finished recover at 22-JUN-12
4、Open数据库
SQL> alter database open;
Database altered.
SQL> select instance_name,status from v$instance;
INSTANCE_NAME STATUS
---------------- ------------
WWL O