Oracle数据库联机日志文件丢失处理方法

Oracle数据库联机日志文件丢失处理方法

试验一：用命令清空日志组方法

1、
查看原来表中数据

SQL>; conn test/test

Connected.

SQL>; select * from test;

TEL

----------

1

2

3

2、插入新数据

SQL>; insert into test values(4);

1 row created.

SQL>; commit;

Commit complete.

SQL>;

3、
正常关闭数据库

4、
利用os command删除所有redo文件

5、
启动数据库

SQL>; startup

ORACLE instance started.

Total System Global Area 353862792 bytes

Fixed Size 730248 bytes

Variable Size 285212672bytes

Database Buffers 67108864bytes

Redo Buffers 811008 bytes

Database mounted.

ORA-00313: open failed for members of log group 1 of thread 1

ORA-00312: online log 1 thread 1: '/T3/ORACLE/oradata/ORA9/redo01.log'

6、
查看当前日志状态

SQL>; select * from v$log;

GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS

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

FIRST_CHANGE# FIRST_TIME

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

1 1 2 104857600 1 YES INACTIVE

487837 01-9月 -05

2 1 4 104857600 1 NO CURRENT

487955 01-9月 -05

3 1 3 104857600 1 YES INACTIVE

487839 01-9月 -05

看来redo01.log不是当前日志，对于这类非当前日志可以直接clear,系统会重新自动生成一个redo文件

7、SQL>;alter database clear logfile group 1;

Database altered.

7、
继续启动db

SQL>; alter database open;

alter database open

*

ERROR at line 1:

ORA-00313: open failed for members of log group 2 of thread 1

ORA-00312: online log 2 thread 1: '/T3/ORACLE/oradata/ORA9/redo02.log'

8、
看来redo也得恢复，但是redo02是当前redo,直接clear是不行的

SQL>; alter database clear logfile group 2;

alter database clear logfile group 2

*

ERROR at line 1:

ORA-00350: log 2 of thread 1 needs to be archived

ORA-00312: online log 2 thread 1: '/T3/ORACLE/oradata/ORA9/redo02.log'

尝试clearunarchived logfile group ,报错：

SQL>; alter database clear unarchived logfile group 2;

alter database clear unarchived logfile group 2

*

ERROR at line 1:

ORA-00313: open failed for members of log group 2 of thread 1

ORA-00312: online log 2 thread 1: '/T3/ORACLE/oradata/ORA9/redo02.log'

ORA-27037: unable to obtain file status

SVR4 Error: 2: No such file or directory

Additional information: 3

看来他是因为找不到这个文件，从有效的备份中cp一个过来看看

SQL>; host cp /T3/ORACLE/oradatabak/redo02* /T3/ORACLE/oradata/ORA9

SQL>; alter database clear unarchived logfile group 2;

Database altered.

搞定……….

9、
按照oracle的某些做法也是可以的

SQL>; alter database clear unarchived logfile group 1 unrecoverabledatafile;

Database altered.

10、但是对于非当前日志就都可以，下面看看redo03

SQL>; alter database clear logfile group 3;

Database altered.

结论：

如果数据库是正常shutdown,非当前日志都可以直接clear来重新生成，而且不丢失数据，因为正常关闭db,数据已经写入dbf文件了。唯独当前日志不可以，当前日志必须首先从有效的备份中拷贝一个日志文件过来，然后用

alter database clear unarchived logfile group n 或alter database clear unarchived logfile group n,除此之外，还可以用下面的方法来做