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:hapy-wuweilong@hotmail.com
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。
