方法四:修改系统参数方法
1、 插入数据
SQL> select * from test;
TEL
----------
1
2
3
4
SQL> insert into test values(5);
1 row created.
SQL> commit;
Commit complete.
SQL>
2、 强行关闭
SQL> shutdown abort
ORACLE instance shut down.
SQL>
3、 手工模拟删除redo
4、 启动db
SQL> startup
ORACLE instance started.
Total System Global Area 353862792 bytes
Fixed Size 730248 bytes
Variable Size 285212672 bytes
Database Buffers 67108864 bytes
Redo Buffers 811008 bytes
Database mounted.
ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: '/T3/ORACLE/oradata/ORA9/redo03.log'
ORA-27037: unable to obtain file status
SVR4 Error: 2: No such file or directory
Additional information: 3
5、 尝试使用前3中方法中最简单的
SQL> recover database until cancel;
ORA-00279: change 550174 generated at 09/02/2005 16:00:19 needed for thread 1
ORA-00289: suggestion : /T3/ORACLE/arch/1_1.dbf
ORA-00280: change 550174 for thread 1 is in sequence #1
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
看来不行
6、 修改init.ora,加入一行
_allow_resetlogs_corruption=true
7、 启动with pfile
SQL> startup
ORACLE instance started.
Total System Global Area 320308312 bytes
Fixed Size 730200 bytes
Variable Size 285212672 bytes
Database Buffers 33554432 bytes
Redo Buffers 811008 bytes
Database mounted.
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open
SQL> host ls /T3/ORACLE/oradata/ORA9/redo*
/T3/ORACLE/oradata/ORA9/redo*: No such file or directory
SQL> alter database open resetlogs;
Database altered.
SQL> host ls /T3/ORACLE/oradata/ORA9/redo*
/T3/ORACLE/oradata/ORA9/redo01.log /T3/ORACLE/oradata/ORA9/redo02.log /T3/ORACLE/oradata/ORA9/redo03.log
8、 检验数据
SQL> select * from test.test;
TEL
----------
1
2
3
4
SQL>
看到了吧,我们前面由于执行了SHUTDOWN ABORT,这时候对数据的修改还没有保存到数据文件中,虽然执行了COMMIT,这个时候还在联机日志中,等待CKPT触发DBWR写入DATAFILE,但是这个时候执行了SHUTDOWN ABORT,redo被删除后,里面的信息也就丢了,造成数据丢失
9、 备份,去掉那个参数
试验五:丢失当前日志组的成员
1、SQL> select * from v$logfile;
GROUP# STATUS TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
3 ONLINE
/T3/ORACLE/oradata/ORA9/redo03.log
2 ONLINE
/T3/ORACLE/oradata/ORA9/redo02.log
1 ONLINE
/T3/ORACLE/oradata/ORA9/redo01.log
GROUP# STATUS TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
1 ONLINE
/T3/ORACLE/oradata/ORA9/redo01a.log
2 ONLINE
/T3/ORACLE/oradata/ORA9/redo02a.log
3 ONLINE
/T3/ORACLE/oradata/ORA9/redo03a.log
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
FIRST_CHANGE# FIRST_TIME
------------- ----------
1 1 2 104857600 2 YES INACTIVE
554599 02-9月 -05
2 1 3 104857600 2 YES INACTIVE
554601 02-9月 -05
3 1 4 104857600 2 NO CURRENT
554603 02-9月 -05
SQL>
3、 模拟插入数据
SQL> conn test/test
Connected.
SQL> select * from test;
TEL
----------
1
2
3
4
SQL> insert into test values(5);
1 row created.
SQL> commit
2 ;
Commit complete.
4、 shutdown db,模拟删除一个当前日志成员
$ cd oradata/ORA9
$ ls redo03*
redo03.log redo03a.log
$ rm redo03a.log
5、 启动db,表面没有错误
SQL> startup
ORACLE instance started.
Total System Global Area 353862792 bytes
Fixed Size 730248 bytes
Variable Size 285212672 bytes
Database Buffers 67108864 bytes
Redo Buffers 811008 bytes
Database mounted.
Database opened.
SQL>
6、 查看日至成员
SQL> select * from v$logfile;
GROUP# STATUS TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
3 ONLINE
/T3/ORACLE/oradata/ORA9/redo03.log
2 ONLINE
/T3/ORACLE/oradata/ORA9/redo02.log
1 ONLINE
/T3/ORACLE/oradata/ORA9/redo01.log
GROUP# STATUS TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
1 ONLINE
/T3/ORACLE/oradata/ORA9/redo01a.log
2 ONLINE
/T3/ORACLE/oradata/ORA9/redo02a.log
3 INVALID ONLINE
/T3/ORACLE/oradata/ORA9/redo03a.log
7、 删除出问题的联机日志文件
SQL> alter database drop logfile member '/T3/ORACLE/oradata/ORA9/redo03a.log';
alter database drop logfile member '/T3/ORACLE/oradata/ORA9/redo03a.log'
*
ERROR at line 1:
ORA-01609: log 3 is the current log for thread 1 - cannot drop members
ORA-00312: online log 3 thread 1: '/T3/ORACLE/oradata/ORA9/redo03.log'
ORA-00312: online log 3 thread 1: '/T3/ORACLE/oradata/ORA9/redo03a.log'
SQL>
看来当前日志成员是不允许删除的
SQL> alter system switch logfile;
System altered.
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
FIRST_CHANGE# FIRST_TIME
------------- ----------
1 1 5 104857600 2 NO CURRENT
557687 02-9月 -05
2 1 3 104857600 2 YES INACTIVE
554601 02-9月 -05
3 1 4 104857600 2 YES ACTIVE
554603 02-9月 -05
SQL> alter database drop logfile member '/T3/ORACLE/oradata/ORA9/redo03a.log';
Database altered.
SQL> alter database add logfile member '/T3/ORACLE/oradata/ORA9/redo03a.log' to group 3;
Database altered.
SQL> select * from v$logfile;
GROUP# STATUS TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
3 ONLINE
/T3/ORACLE/oradata/ORA9/redo03.log
2 ONLINE
/T3/ORACLE/oradata/ORA9/redo02.log
1 ONLINE
/T3/ORACLE/oradata/ORA9/redo01.log
GROUP# STATUS TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
1 ONLINE
/T3/ORACLE/oradata/ORA9/redo01a.log
2 ONLINE
/T3/ORACLE/oradata/ORA9/redo02a.log
3 INVALID ONLINE
/T3/ORACLE/oradata/ORA9/redo03a.log
看来还得切换一下日至
SQL> alter system switch logfile;
System altered.
SQL> select * from v$logfile;
GROUP# STATUS TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
3 ONLINE
/T3/ORACLE/oradata/ORA9/redo03.log
2 ONLINE
/T3/ORACLE/oradata/ORA9/redo02.log
1 ONLINE
/T3/ORACLE/oradata/ORA9/redo01.log
GROUP# STATUS TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
1 ONLINE
/T3/ORACLE/oradata/ORA9/redo01a.log
2 ONLINE
/T3/ORACLE/oradata/ORA9/redo02a.log
3 ONLINE
/T3/ORACLE/oradata/ORA9/redo03a.log
至此,大功告成…………….
结论:
只要日志组的member不是一个,出现前面的4种可能性是非常小的,即使出现了也有相应的恢复方法,所以不必惊慌;
如果memer多于1个,即使坏了其中的几个,也不会 影响数据库的正常启动,启动后,再进行相应的操作即可, 所以这个时候每天察看alert.log就显得非常重要了。
Remen
2005.9.2