OnlineRedoLog损坏处理实验（中）

下面我们进行更复杂情况的处理，就是非一致性关闭的情况下日志损坏的情况。这种情况是很有实际意义的。因为在出现错误的时候，Oracle可能不会允许一致性关闭。没有经验的处理人员往往会贸然的强制关闭，我们获得到的场景往往也是非一致的情况。

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4、非一致性关闭非当前日志组处理——Inactive日志组

非一致性关闭情况下，online日志组全员损坏是很复杂的，也是潜在会有数据损失的。我们这里说的非一致性关闭，就是shutdown abort或者强制断电之后。由于Oracle数据库采用写日志在先的策略，关闭点上我们不能保证脏块（Dirty Block）全都被写入到数据文件，各个数据文件和控制文件在SCN时间上保证一致性。

但是当数据库重新启动时，在open阶段，Oracle会进行instance recovery，从最后一个增量检查点check point追起，重演事务并且回滚事务。Instance Recovery过程也被称为前滚回滚过程，或者成为Cache Recovery和Transaction Recovery过程。

如果进行不一致关闭就会需要进行instance recovery，进行instance recovery最需要的内容就是online redo log。如果我们删除online redo log group恰好是进行instance recovery所需要的，那么我们就只能牺牲掉一部分数据，进行不完全恢复。

我们删除的非当前日志组也有很大风险，因为在日志切换成非当前日志之后，日志组有一段时间对应脏块是不能写入到数据文件中的。这也就是日志文件的active状态。本节讨论非当前日志成员被删除的情况，具体划分为Inactive日志组和非Inactive日志组。

我们下面实验选择Oracle 11g的Linux版本进行。

SQL> select * from v$version;

BANNER

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

Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production

PL/SQL Release 11.2.0.1.0 - Production

CORE 11.2.0.1.0 Production

当前日志情况如下：

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

GROUP# STATUS ARCHIVED SEQUENCE#

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

1 INACTIVE YES 108

2 CURRENT NO 110

3 INACTIVE YES 109

SQL> drop table t;

Table dropped

SQL> create table t as select * from dba_objects;

Table created

SQL> select group#, status, member from v$logfile;

GROUP# STATUS MEMBER

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

3 /u01/oradata/WILSON/onlinelog/o1_mf_3_7xt456o0_.log

3 /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_3_7xt45bvp_.log

2 /u01/oradata/WILSON/onlinelog/o1_mf_2_7xt44w3k_.log

2 /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_2_7xt450rv_.log

1 /u01/oradata/WILSON/onlinelog/o1_mf_1_870jlj6v_.log

1 /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_1_870jljvk_.log

6 rows selected

强制停机之后，删除日志组1对象。

[oracle@bspdev ~]$ sqlplus /nolog

SQL*Plus: Release 11.2.0.1.0 Production on Sat Oct 6 22:27:57 2012

SQL> conn / as sysdba

Connected.

SQL> shutdown abort

ORACLE instance shut down.

[oracle@bspdev ~]$ mv /u01/oradata/WILSON/onlinelog/o1_mf_1_870jlj6v_.log /u01/oradata/WILSON/onlinelog/redogroup1.log

[oracle@bspdev ~]$ rm /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_1_870jljvk_.log

[oracle@bspdev ~]$

重新启动之后，无法找到对应的日志文件，直接报错。

SQL> conn / as sysdba

Connected to an idle instance.

SQL> startup

ORACLE instance started.

Total System Global Area 849530880 bytes

Fixed Size 1339824 bytes

Variable Size 562040400 bytes

Database Buffers 281018368 bytes

Redo Buffers 5132288 bytes

Database mounted.

ORA-03113: end-of-file on communication channel

Process ID: 5059

Session ID: 1 Serial number: 5

ORA-27037: unable to obtain file status

Linux Error: 2: No such file or directory

Additional information: 3

Errors in file /u01/diag/rdbms/wilson/wilson/trace/wilson_ora_5059.trc:

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

ORA-00312: online log 1 thread 1: '/u01/oradata/WILSON/onlinelog/o1_mf_1_870jlj6v_.log'

ORA-00312: online log 1 thread 1: '/u01/flash_recovery_area/WILSON/onlinelog/o1_mf_1_870jljvk_.log'

USER (ospid: 5059): terminating the instance due to error 313

Instance terminated by USER, pid = 5059

重新启动到mount状态，进行处理。

SQL> conn / as sysdba

Connected to an idle instance.

SQL> startup mount

ORACLE instance started.

Total System Global Area 849530880 bytes

Fixed Size 1339824 bytes

Variable Size 562040400 bytes

Database Buffers 281018368 bytes

Redo Buffers 5132288 bytes

Database mounted.

SQL> select open_mode from v$database;

OPEN_MODE

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

MOUNTED

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

GROUP# STATUS ARC SEQUENCE#

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

1 INACTIVE YES 108

3 INACTIVE YES 109

2 CURRENT NO 110

SQL> select checkpoint_change#, last_change# from v$datafile;

CHECKPOINT_CHANGE# LAST_CHANGE#

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

1950243 1950243

7 rows selected.

SQL> select checkpoint_change# from v$datafile_header;

CHECKPOINT_CHANGE#

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

1950243

7 rows selected.

SQL>

虽然启动失效，但是我们没有看到很严重的一致性问题。我们尝试启动数据库。

SQL> alter database clear logfile group 1;

Database altered.

SQL> alter database open;

Database altered.

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

GROUP# STATUS ARCHIVED SEQUENCE#

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

1 CURRENT NO 111

2 INACTIVE YES 110

3 INACTIVE YES 109

这种场景是比较好处理的。下面我们讨论如果是Active状态的日志被删除如何？

5、非一致性关闭非当前日志组处理——Active日志组

我们构造出Active日志组对象。

SQL> select group#, status, member from v$logfile;

GROUP# STATUS MEMBER

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

3 /u01/oradata/WILSON/onlinelog/o1_mf_3_7xt456o0_.log

3 /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_3_7xt45bvp_.log

2 /u01/oradata/WILSON/onlinelog/o1_mf_2_7xt44w3k_.log

2 /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_2_7xt450rv_.log

1 /u01/oradata/WILSON/onlinelog/o1_mf_1_870kg322_.log

1 /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_1_870kg3mr_.log

6 rows selected

SQL> alter system switch logfile;

System altered

SQL> alter system switch logfile;

System altered

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

GROUP# STATUS ARCHIVED SEQUENCE#

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

1 CURRENT NO 114

2 ACTIVE YES 113

3 INACTIVE YES 112

之后强制关闭数据库，删除对应的日志组2。

SQL> shutdown abort;

ORACLE instance shut down.

SQL>

[oracle@bspdev trace]$ mv /u01/oradata/WILSON/onlinelog/o1_mf_2_7xt44w3k_.log /u01/oradata/WILSON/onlinelog/redogroup2.log

[oracle@bspdev trace]$ rm /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_2_7xt450rv_.log

重新启动数据库。

SQL> conn / as sysdba

Connected to an idle instance.

SQL> startup

ORACLE instance started.

Total System Global Area 849530880 bytes

Fixed Size 1339824 bytes

Variable Size 562040400 bytes

Database Buffers 281018368 bytes

Redo Buffers 5132288 bytes

Database mounted.

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

ORA-00312: online log 2 thread 1:

'/u01/flash_recovery_area/WILSON/onlinelog/o1_mf_2_7xt450rv_.log'

ORA-27037: unable to obtain file status

Linux Error: 2: No such file or directory

Additional information: 3

ORA-00312: online log 2 thread 1:

'/u01/oradata/WILSON/onlinelog/o1_mf_2_7xt44w3k_.log'

ORA-27037: unable to obtain file status

Linux Error: 2: No such file or directory

Additional information: 3

SQL> select open_mode from v$database;

OPEN_MODE

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

MOUNTED

检查文件状态情况。

SQL> select checkpoint_change#, last_change# from v$datafile;

CHECKPOINT_CHANGE# LAST_CHANGE#

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

1970578

7 rows selected.

SQL> select checkpoint_change# from v$datafile_header;

CHECKPOINT_CHANGE#

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

1970578

7 rows selected.

从v$datafile的情况，我们就可以看出关闭是不完全关闭情况。我们只能尝试进行恢复。

SQL> recover database;

ORA-00279: change 1970578 generated at 10/06/2012 22:59:02 needed for thread 1

ORA-00289: suggestion :

/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_113_870kwzkl_.arc

ORA-00280: change 1970578 for thread 1 is in sequence #113

Specify log: {=suggested | filename | AUTO | CANCEL}

cancel

Media recovery cancelled.

提出恢复使用sequence#=113的日志，但是这个恰恰是被删除的对象。所以，只能退而求其次选择使用不完全恢复。

SQL> recover database until cancel;

ORA-00279: change 1970578 generated at 10/06/2012 22:59:02 needed for thread 1

ORA-00289: suggestion :

/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_113_870kwzkl_.arc

ORA-00280: change 1970578 for thread 1 is in sequence #113

Specify log: {=suggested | filename | AUTO | CANCEL}

auto

ORA-00279: change 1970779 generated at 10/06/2012 23:00:47 needed for thread 1

ORA-00289: suggestion :

/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_114_%u_.arc

ORA-00280: change 1970779 for thread 1 is in sequence #114

ORA-00278: log file

'/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_113_870kwzkl_.arc

' no longer needed for this recovery

ORA-00308: cannot open archived log

'/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_114_%u_.arc'

ORA-27037: unable to obtain file status

Linux Error: 2: No such file or directory

Additional information: 3

ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below

ORA-01194: file 1 needs more recovery to be consistent

ORA-01110: data file 1:

'/u01/oradata/WILSON/datafile/o1_mf_system_7xt3yzhj_.dbf'

SQL> alter database open resetlogs;

alter database open resetlogs

ERROR at line 1:

ORA-01194: file 1 needs more recovery to be consistent

ORA-01110: data file 1:

'/u01/oradata/WILSON/datafile/o1_mf_system_7xt3yzhj_.dbf'

尝试使用RMAN SCN方式打开。

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

GROUP# SEQUENCE# FIRST_CHANGE#

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

1 114 1970779

3 112 1950574

2 113 1970577

RMAN> recover database until sequence 112;

Starting recover at 06-OCT-12

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=18 device type=DISK

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of recover command at 10/06/2012 23:19:42

RMAN-06556: datafile 1 must be restored from backup older than SCN 1950574

System文件的日期已经超过了recover范畴。只能尝试利用RMAN备份进行还原。

RMAN> restore database;

Starting restore at 06-OCT-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/oradata/WILSON/datafile/o1_mf_system_7xt3yzhj_.dbf

channel ORA_DISK_1: restoring datafile 00002 to /u01/oradata/WILSON/datafile/o1_mf_sysaux_7xt3yzkb_.dbf

channel ORA_DISK_1: restoring datafile 00003 to /u01/oradata/WILSON/datafile/o1_mf_undotbs1_7xt3yzl5_.dbf

channel ORA_DISK_1: restoring datafile 00004 to /u01/oradata/WILSON/datafile/o1_mf_users_805nxydh_.dbf

channel ORA_DISK_1: restoring datafile 00005 to /u01/oradata/WILSON/datafile/o1_mf_example_7xt46m9x_.dbf

channel ORA_DISK_1: restoring datafile 00006 to /u01/oradata/WILSON/datafile/o1_mf_nbscommo_820frtg1_.dbf

channel ORA_DISK_1: restoring datafile 00007 to /u01/oradata/WILSON/datafile/o1_mf_nbscommo_820ft5y5_.dbf

channel ORA_DISK_1: reading from backup piece /u01/flash_recovery_area/WILSON/backupset/2012_10_06/o1_mf_nnndf_TAG20121006T220912_870gwjoy_.bkp

channel ORA_DISK_1: piece handle=/u01/flash_recovery_area/WILSON/backupset/2012_10_06/o1_mf_nnndf_TAG20121006T220912_870gwjoy_.bkp tag=TAG20121006T220912

channel ORA_DISK_1: restored backup piece 1

channel ORA_DISK_1: restore complete, elapsed time: 00:02:46

Finished restore at 06-OCT-12

--进行部分恢复

RMAN> recover database until sequence 112;

Starting recover at 06-OCT-12

using channel ORA_DISK_1

starting media recovery

archived log for thread 1 with sequence 106 is already on disk as file /u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_106_870gzbfg_.arc

archived log for thread 1 with sequence 107 is already on disk as file /u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_107_870jlysq_.arc

archived log for thread 1 with sequence 108 is already on disk as file /u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_108_870jo98m_.arc

archived log for thread 1 with sequence 109 is already on disk as file /u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_109_870jx2gj_.arc

archived log for thread 1 with sequence 110 is already on disk as file /u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_110_870kgmdp_.arc

archived log for thread 1 with sequence 111 is already on disk as file /u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_111_870knhwb_.arc

archived log file name=/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_106_870gzbfg_.arc thread=1 sequence=106

archived log file name=/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_107_870jlysq_.arc thread=1 sequence=107

archived log file name=/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_108_870jo98m_.arc thread=1 sequence=108

archived log file name=/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_109_870jx2gj_.arc thread=1 sequence=109

archived log file name=/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_110_870kgmdp_.arc thread=1 sequence=110

archived log file name=/u01/flash_recovery_area/WILSON/archivelog/2012_10_06/o1_mf_1_111_870knhwb_.arc thread=1 sequence=111

media recovery complete, elapsed time: 00:00:20

Finished recover at 06-OCT-12

明显，得益于归档模式和备份集合。我们似乎成功的完成了recover过程。下面我们尝试开启数据库，注意这里已经是incomplete恢复了，我们必须承担这部分的数据损失。

SQL> conn / as sysdba

Connected.

SQL> alter database open resetlogs;

Database altered.

SQL> select group#, status, member from v$logfile;

GROUP# STATUS MEMBER

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

3 /u01/oradata/WILSON/onlinelog/o1_mf_3_870n4lsg_.log

3 /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_3_870n4o31_.log

2 /u01/oradata/WILSON/onlinelog/o1_mf_2_870n48hc_.log

2 /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_2_870n4dtl_.log

1 /u01/oradata/WILSON/onlinelog/o1_mf_1_870n42n1_.log

1 /u01/flash_recovery_area/WILSON/onlinelog/o1_mf_1_870n44z3_.log

6 rows selected

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

GROUP# STATUS ARCHIVED SEQUENCE#

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

1 CURRENT NO 1

2 UNUSED YES 0

3 UNUSED YES 0

总结：当我们incomplete关闭数据库，又删除了Active状态日志组成员之后，我们必须要承担对应的数据损失，一部分数据可能因此丢失。笔者之后的处理，是借助之前rman的一个备份集合，进行非完全恢复到最后一个可以找到的日志文件组。这里，我们再次强调归档模式和备份的重要性。

分享标题：OnlineRedoLog损坏处理实验（中）
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OnlineRedoLog损坏处理实验（中）

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