探索ORACLE不完全恢复之--基于cancel的恢复 第二篇

探索ORACLE不完全恢复之--基于cancel的恢复 第二篇

作者：吴伟龙   Name：Prodence Woo

QQ：286507175  msn:[email protected]

基于cancel 的不一致性恢复（归档丢失） 第二篇

   主要适用于：基于Cancel的不完全恢复适用场景：Recover时，所需的某个归档日志损坏，或主机断电，current状态的联机日志损坏。

 

创建测试表

    创建wwl002表，切换日志，再创建新的wwl003表，主机断电，删除当前日志，模拟文件损坏。

SQL> conn wwl/wwl

Connected.

 

SQL> select * from tab;

TNAME                          TABTYPE  CLUSTERID

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

WWL001                         TABLE

 

SQL> create table WWL002 as select *from wwl001;

Table created.

 

SQL> conn / as sysdba

Connected.

 

切换日志

SQL> alter system switch logfile;

System altered.

 

后再创建第二张表

SQL> conn wwl/wwl

Connected.

 

SQL> create table wwl003 as select *from wwl001;

Table created.

 

查看当前日志组，确定当前活动的日志组，是组4

SQL> conn / as sysdba

Connected.

SQL> set line 200

SQL> select * from v$log;

 

   GROUP#    THREAD#  SEQUENCE#     BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM

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

         4          1          2 134217728          2 YES ACTIVE                 1716929 30-JUL-12

        5          1          1 134217728          2 YES INACTIVE               1692728 27-JUL-12

        6          1          3 134217728          2 NO  CURRENT                1720396 30-JUL-12

        7          1          0 134217728          2 YES UNUSED                       0

 

定位当前日志组的日志文件，有两个。

 SQL> col member format a30

SQL> select * from v$logfile;

 

   GROUP# STATUS  TYPE    MEMBER                         IS_

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

        7         ONLINE  /DBBak2/oradata/WWL/redo7a.log NO

        7         ONLINE  /DBBak2/oradata/WWL/redo7b.log NO

        6         ONLINE  /DBBak2/oradata/WWL/redo6a.log NO

        6         ONLINE  /DBBak2/oradata/WWL/redo6b.log NO

        5 STALE   ONLINE  /DBBak2/oradata/WWL/redo5a.log NO

        5 STALE   ONLINE  /DBBak2/oradata/WWL/redo5b.log NO

         4         ONLINE /DBBak2/oradata/WWL/redo4a.log NO

         4         ONLINE /DBBak2/oradata/WWL/redo4b.log NO

 

8 rows selected.

 

删除当前日志组文件，模拟在线事务丢失：

SQL> !rm -f/DBBak2/oradata/WWL/redo4a.log

SQL> !rm -f/DBBak2/oradata/WWL/redo4b.log

 

模拟服务器断电

SQL> shutdown abort;

ORACLE instance shut down.

 

恢复步骤:

1、尝试启动数据库的时候报当前日志丢失。

SQL> startup

ORACLE instance started.

 

Total System Global Area  100663296 bytes

Fixed Size                  1217884 bytes

Variable Size              88083108 bytes

Database Buffers            8388608 bytes

Redo Buffers                2973696 bytes

Database mounted.

ORA-00313: open failedfor members of log group 4 of thread 1

ORA-00312: online log 4thread 1: '/DBBak2/oradata/WWL/redo4b.log'

ORA-27037: unable toobtain file status

Linux Error: 2: No suchfile or directory

Additional information: 3

ORA-00312: online log 4thread 1: '/DBBak2/oradata/WWL/redo4a.log'

ORA-27037: unable toobtain file status

Linux Error: 2: No suchfile or directory

Additional information: 3

 

2、尝试Clear redo4

SQL> alter database clear logfile group4;

alter database clear logfile group 4

*

ERROR at line 1:

ORA-01624: log 4 needed for crash recoveryof instance WWL (thread 1)

ORA-00312: online log 4 thread 1:'/DBBak2/oradata/WWL/redo4a.log'

ORA-00312: online log 4 thread 1:'/DBBak2/oradata/WWL/redo4b.log'

 

3、在当前库做基于Cancel的不完全恢复

SQL> recover database until cancel;

ORA-00279: change 1716930 generated at07/30/2012 11:03:51 needed for thread 1

ORA-00289: suggestion :/DBSoft/product/10.2.0/db_1/dbs/arch1_2_789761098.dbf

ORA-00280: change 1716930 for thread 1 isin sequence #2

 

 

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

auto

ORA-00279: change 1720396 generated at07/30/2012 13:37:21 needed for thread 1

ORA-00289: suggestion :/DBSoft/product/10.2.0/db_1/dbs/arch1_3_789761098.dbf

ORA-00280: change 1720396 for thread 1 isin sequence #3

ORA-00278: log file'/DBSoft/product/10.2.0/db_1/dbs/arch1_2_789761098.dbf' no longer needed forthis recovery

 

 

ORA-00308: cannot open archived log'/DBSoft/product/10.2.0/db_1/dbs/arch1_3_789761098.dbf'

ORA-27037: unable to obtain file status

Linux Error: 2: No such file or directory

Additional information: 3

 

 

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

ORA-01194: file 1 needs more recovery to beconsistent

ORA-01110: data file 1:'/DBBak2/oradata/WWL/system01.dbf'

 

做完恢复之后必须使用resetlogs选项打开数据库：

SQL> alter database open resetlogs;

alter database open resetlogs

*

ERROR at line 1:

ORA-01194: file 1 needs more recovery to beconsistent

ORA-01110: data file 1:'/DBBak2/oradata/WWL/system01.dbf'

 

    恢复之后，使用Resetlogs选项，仍无法打开数据库，提示数据文件不一致，System表空间需要进一步的恢复。
    当前日志损坏时，不能基于当前的数据库做不完全恢复。只能用以前的备份，做一个基于Cancel的不完全恢复。

 

重建下控制文件：

SQL> CREATE CONTROLFILE REUSE DATABASE"WWL" RESETLOGS  ARCHIVELOG

   MAXLOGFILES 16

   MAXLOGMEMBERS 3

   '/DBBak2/oradata/WWL/redo4a.log',

   MAXDATAFILES 100

   MAXINSTANCES 8

 GROUP 5 (

   MAXLOGHISTORY 292

LOGFILE

 GROUP 4 (

   '/DBBak2/oradata/WWL/redo4a.log',

   '/DBBak2/oradata/WWL/redo4b.log'

 GROUP 6 (

  )SIZE 128M,

 GROUP 5 (

   '/DBBak2/oradata/WWL/redo5a.log',

   '/DBBak2/oradata/WWL/redo5b.log'

   '/DBBak2/oradata/WWL/redo7b.log'

  )SIZE 128M,

 GROUP 6 (

   '/DBBak2/oradata/WWL/redo6a.log',

   '/DBBak2/oradata/WWL/redo6b.log'

  )SIZE 128M,

 GROUP 7 (

   '/DBBak2/oradata/WWL/redo7a.log',

   '/DBBak2/oradata/WWL/redo7b.log'

  )SIZE 128M

-- STANDBY LOGFILE

DATAFILE

 '/DBBak2/oradata/WWL/system01.dbf',

 '/DBBak2/oradata/WWL/undotbs01.dbf',

 '/DBBak2/oradata/WWL/sysaux01.dbf',

 '/DBBak2/oradata/WWL/users01.dbf',

 '/DBBak2/oradata/WWL/wwl001',

 '/DBBak2/oradata/WWL/wwl002',

 '/DBBak2/oradata/WWL/wwl003'

CHARACTER SET ZHS16CGB231280

 34  ;

 

Control file created.

 

再次打开，结果还是不行

SQL> alter database open resetlogs;

alter database open resetlogs

*

ERROR at line 1:

ORA-01194: file 1 needs more recovery to beconsistent

ORA-01110: data file 1:'/DBBak2/oradata/WWL/system01.dbf'

 

可以尝试使用_allow_resetlogs_corruption隐含参数来打开数据库

SQL> alter system set"_allow_resetlogs_corruption"=true scope=spfile;

System altered.

 

修改完参数之后重启数据库到mount状态

SQL> shutdown immediate

ORA-01109: database not open

Database dismounted.

ORACLE instance shut down.

 

SQL> startup;

ORACLE instance started.

 

Total System Global Area  100663296 bytes

Fixed Size                  1217884 bytes

Variable Size              88083108 bytes

Database Buffers            8388608 bytes

Redo Buffers                2973696 bytes

Database mounted.

ORA-01589: must use RESETLOGS orNORESETLOGS option for database open

 

同样以resetlogs模式启动数据库

SQL> alter database open resetlogs;

Database altered.

 

一定记得关闭该参数

SQL> alter system set"_allow_resetlogs_corruption"=FALSE scope=spfile;

System altered.

 

让参数关闭生效，再次启动数据库

SQL> startup force;

ORACLE instance started.

 

Total System Global Area  100663296 bytes

Fixed Size                  1217884 bytes

Variable Size              88083108 bytes

Database Buffers            8388608 bytes

Redo Buffers                2973696 bytes

Database mounted.

Database opened.

 

检查_allow_resetlogs_corruption 隐含参数是否关闭，确定已经关闭

SQL> show parameter_allow_resetlogs_corruption

NAME                                 TYPE        VALUE

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

_allow_resetlogs_corruption          boolean     FALSE

SQL>

 

因为重建了控制文件，默认是没有制定temp表空间，这里制定下：

SQL> ALTER TABLESPACE TEMP01 ADDTEMPFILE '/DBBak2/oradata/WWL/temp01.dbf' REUSE;

Tablespace altered.

 

检查数据

SQL> conn wwl/wwl

Connected.

 

 

SQL> select * from tab;

TNAME                          TABTYPE  CLUSTERID

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

WWL001                         TABLE

WWL002                         TABLE

 

可以看到表WWL002存在，表WWL003不存在。因为WWL003的创建，是保存在当前REDO日志中的，而当前REDO日志损坏，所有当前日志中保存的操作全部丢失了。
    归档日志、或者REDO日志损失，数据库就只能恢复到丢失的日志之前了。