Redo current损坏

   如果损坏的是current redo log （select group#,sequence#,archived,status from v$log;）

有两种情况：

A、   数据库是正常关闭的。当前日志组的损坏就可以直接用alter database clear unarchived logfile group n来重建。

启动数据库到mount状态

SQL> select group#,sequence#,archived,status from v$log;

GROUP#  SEQUENCE# ARC STATUS

---------- ---------- --- ----------------

1          0 YES UNUSED

3          3 NO  CURRENT

2          2 YES INACTIVE

SQL> alter database clear unarchived logfile group 3;

Database altered.

SQL> alter database open;

Database altered.

B、   如果数据库是非正常关闭（shutdown abort），current redo log 损坏，最好的恢复办法就是通过不完全恢复，可以保证数据库的一致性，但会丢失数据。

SQL> select group#,sequence#,archived,status from v$log;

GROUP#  SEQUENCE# ARC STATUS

---------- ---------- --- ----------------

1         32 NO  CURRENT

3         31 YES INACTIVE

2         30 YES INACTIVE

执行clear logfile group 1会报如下错误。

SQL> alter database clear unarchived logfile group 1;

ERROR at line 1:

ORA-01624: log 1 needed for crash recovery of instance orcl (thread 1)

ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/orcl/redo01.log'

此时需要进行不完全恢复

RMAN> restore database;

Starting restore at 02-DEC-12

using channel ORA_DISK_1

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: restoring datafile 00002 to /u01/app/oracle/oradata/orcl/sysaux01.dbf

channel ORA_DISK_1: restoring datafile 00003 to /u01/app/oracle/oradata/orcl/undotbs01.dbf

channel ORA_DISK_1: restoring datafile 00004 to /u01/app/oracle/oradata/orcl/users01.dbf

channel ORA_DISK_1: reading from backup piece /u01/app/oracle/backup/full_ORCL_20121202_12_1.bak

channel ORA_DISK_1: piece handle=/u01/app/oracle/backup/full_ORCL_20121202_12_1.bak tag=TAG20121202T141019

channel ORA_DISK_1: restored backup piece 1

channel ORA_DISK_1: restore complete, elapsed time: 00:00:45

Finished restore at 02-DEC-12

SQL> recover database until cancel;

ORA-00279: change 274326 generated at 12/02/2012 14:10:20 needed for thread 1

ORA-00289: suggestion : /u01/app/oracle/oradata/arch/1_22_800911110.dbf

ORA-00280: change 274326 for thread 1 is in sequence #22

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}

Auto

…………

ORA-00279: change 274396 generated at 12/02/2012 14:11:18 needed for thread 1

ORA-00289: suggestion : /u01/app/oracle/oradata/arch/1_32_800911110.dbf

ORA-00280: change 274396 for thread 1 is in sequence #32

ORA-00278: log file '/u01/app/oracle/oradata/arch/1_31_800911110.dbf' no longer

needed for this recovery

ORA-00308: cannot open archived log

'/u01/app/oracle/oradata/arch/1_32_800911110.dbf'

ORA-27037: unable to obtain file status

Linux-x86_64 Error: 2: No such file or directory

Additional information: 3

SQL> alter database open resetlogs;

Database altered.

恢复到当前日志的SEQUENCE#为32，不完全恢复结束。这种办法恢复的数据库会丢失当前联机日志中的事务数据。恢复成功之后，记得再做一次数据库的全备份。