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使用bbed修改文件头，推进scn，恢复offlinedrop的数据文件

来源：学习哇

最近处理了一起由于用户操作错误导致的数据库无法打开的情况。用户数据库为windows bit，数据库版本为11.2.0.1，非归档模式。由于异常断电，数据库无法正常打开，而且经过用户的判断使用了错误的offline drop操作。导致数据库打开后，日志文件切换过多，

最近处理了一起由于用户操作错误导致的数据库无法打开的情况。

用户数据库为windows bit，数据库版本为11.2.0.1，非归档模式。由于异常断电，数据库无法正常打开，而且经过用户的判断使用了错误的offline drop操作。导致数据库打开后，日志文件切换过多，无法使用recover命令。

因为中间没有做其他操作，所以接到case后，这里将受损的几个数据文件copy到linux下使用bbed进行修改，再copy回windows，成功跳过recover，打开了offline drop的数据文件。

情景还原：

sys@UTF8A> select name ,checkpoint_change# from v$datafile ;
 
NAME CHECKPOINT_CHANGE#
--------------------------------------------------------------------
/u01/apps/oracle/oradata/utf8a/system01.dbf 1040256
/u01/apps/oracle/oradata/utf8a/sysaux01.dbf 1040256
/u01/apps/oracle/oradata/utf8a/undotbs01.dbf 1040256
/u01/apps/oracle/oradata/utf8a/users01.dbf 10396
 
 
sys@UTF8A> select sequence#, group#,first_change#,statusfrom v$log ;
 
 SEQUENCE# GROUP# FIRST_CHANGE# STATUS
---------- ---------- -----------------------------
 19 1 1040256 CURRENT
 17 2 1040250 INACTIVE
 18 3 1040253 INACTIVE
 
 
sys@UTF8A> recover datafile 4 ;
ORA-00279: change 10396 generated at03/30/2015 09:31:05 needed for thread 1
ORA-002: suggestion :/u01/apps/oracle/product/11.2.0/dbhome_1/dbs/arch1_12_827004096.dbf
ORA-00280: change 10396 for thread 1 isin sequence #12
 
 
Specify log: {=suggested |filename | AUTO | CANCEL}
auto
ORA-00308: cannot open archived log'/u01/apps/oracle/product/11.2.0/dbhome_1/dbs/arch1_12_827004096.dbf'
ORA-27037: unable to obtain file status
Linux-x86_ Error: 2: No such file ordirectory
Additional information: 3
 
 
ORA-00308: cannot open archived log'/u01/apps/oracle/product/11.2.0/dbhome_1/dbs/arch1_12_827004096.dbf'
ORA-27037: unable to obtain file status
Linux-x86_ Error: 2: No such file ordirectory
Additional information: 3

sequence已经过去，无法执行恢复，所以这里只能使用bbed修改文件头了。归档以及备份真的很重要。

block为8192。

flist：

1/u01/apps/oracle/oradata/utf8a/system01.dbf 754974720

2/u01/apps/oracle/oradata/utf8a/sysaux01.dbf 566231040

3/u01/apps/oracle/oradata/utf8a/undotbs01.dbf 83886080

4/u01/apps/oracle/oradata/utf8a/users01.dbf 9175040

如何初始化bbed环境，以及各种bbed版本的下载，见我的博客

http://blog.csdn.net/renfengjun/article/details/7944629

这里不再重复赘述。

先关闭数据库并且启动到mount状态。

sys@UTF8A> selectfile#,change#,online_status from v$recover_file ;
 
 FILE# CHANGE# ONLINE_
---------- ---------- -------
 4 10396 OFFLINE
 
sys@UTF8A> select name ,checkpoint_change# from v$datafile ;
 
NAME CHECKPOINT_CHANGE#
--------------------------------------------------------------------
/u01/apps/oracle/oradata/utf8a/system01.dbf 10415
/u01/apps/oracle/oradata/utf8a/sysaux01.dbf 10415
/u01/apps/oracle/oradata/utf8a/undotbs01.dbf 10415
/u01/apps/oracle/oradata/utf8a/users01.dbf 10396

记得修改前先备份所有的数据库文件。

BBED> set file 4
 FILE# 4
 
BBED> p kcvfhckp
struct kcvfhckp, 36 bytes @484 
 struct kcvcpscn, 8 bytes @484 
 ub4 kscnbas @484 0x000fde18
 ub2 kscnwrp @488 0x0000
 ub4 kcvcptim @492 0x34321859
 ub2 kcvcpthr @496 0x0001
 union u, 12 bytes @500 
 struct kcvcprba, 12 bytes @500 
 ub4 kcrbaseq @500 0x0000000c
 ub4 kcrbabno @504 0x00000015
 ub2 kcrbabof @508 0x0010
 ub1 kcvcpetb[0] @512 0x02
 ub1 kcvcpetb[1] @513 0x00
 ub1 kcvcpetb[2] @514 0x00
 ub1 kcvcpetb[3] @515 0x00
 ub1 kcvcpetb[4] @516 0x00
 ub1 kcvcpetb[5] @517 0x00
 ub1 kcvcpetb[6] @518 0x00
 ub1 kcvcpetb[7] @519 0x00

注意offset 484 ， kscnbas为数据文件现在的scn。

使用计算器计算后0x000fde18，得到的十进制数字为10396，确认无误，只要修改scn为最新的10415，即可打开损坏的数据文件。

BBED> d /v dba 4,1 offset 484 count 16
 File: /u01/apps/oracle/oradata/utf8a/users01.dbf(4)
 Block: 1 Offsets: 484 to 499 Dba:0x01000001
-------------------------------------------------------
 18de0f00 00000000 59183234 01000000 l ......Y.24....
 
 <16 bytes per line>

因为是这里为linux x ，为little endian。

10396=18de0f00

10415=9ce40f00

直接修改即可。

BBED> set【本文来自鸿网互联 (http://www.68idc.cn)】 mode edit
 MODE Edit
 
BBED> m /x 9ce40f dba 4,1 offset 484
 File:/u01/apps/oracle/oradata/utf8a/users01.dbf (4)
 Block: 1 Offsets: 484 to 499 Dba:0x01000001
------------------------------------------------------------------------
 9ce40f00 00000000 59183234 01000000
 
 <32 bytes per line>
 
 
 
BBED> m /x 9ce40f dba 4,1 offset 484
 File: /u01/apps/oracle/oradata/utf8a/users01.dbf(4)
 Block: 1 Offsets: 484 to 499 Dba:0x01000001
------------------------------------------------------------------------
 9ce40f00 00000000 59183234 01000000
 
 <32 bytes per line>
 
BBED> sum
Check value for File 4, Block 1:
current = 0x5f67, required = 0x65e3
 
BBED> sum apply
Check value for File 4, Block 1:
current = 0x65e3, required = 0x65e3

完成任务

 
sys@UTF8A> alter database datafile 4online ;
 
Database altered.
 
sys@UTF8A> selectfile#,change#,online_status from v$recover_file ;
 
 FILE# CHANGE# ONLINE_
---------- ---------- -------
 4 10415 ONLINE
 
sys@UTF8A> alter database datafile 4online ;
 
Database altered.
 
sys@UTF8A> alter database open ;
alter database open
*
ERROR at line 1:
ORA-01113: file 4 needs media recovery
ORA-01110: data file 4:'/u01/apps/oracle/oradata/utf8a/users01.dbf'
 
 
sys@UTF8A> recover datafile 4 ;
Media recovery complete.
sys@UTF8A> alter database open ;
 
Database altered.
 
sys@UTF8A> select * from scott.emp where rownum<2 ;
 
 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- -------------------- ----------
 7369 SMITH CLERK 7902 17-DEC-80 800 20