使用bbed修改文件头，推进scn，恢复offline drop的数据文件

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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 64bit，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$datafile ; NAME                                              CHECKPOINT_CHANGE#--------------------------------------------------------------------/u01/apps/oracle/oradata/utf8a/system01.dbf                   1040256/u01/apps/oracle/oradata/utf8a/sysaux01.dbf                   1040256/u01/apps/oracle/oradata/utf8a/undotbs01.dbf                  1040256/u01/apps/oracle/oradata/utf8a/users01.dbf                    1039896  sys@UTF8A> select sequence#, group#,first_change#,statusfrom v$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 1039896 generated at03/30/2015 09:31:05 needed for thread 1ORA-00289: suggestion :/u01/apps/oracle/product/11.2.0/dbhome_1/dbs/arch1_12_827004096.dbfORA-00280: change 1039896 for thread 1 isin sequence #12  Specify log: {<RET>=suggested |filename | AUTO | CANCEL}autoORA-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 statusLinux-x86_64 Error: 2: No such file ordirectoryAdditional 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 statusLinux-x86_64 Error: 2: No such file ordirectoryAdditional 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$recover_file ;     FILE#    CHANGE# ONLINE_---------- ---------- -------        4    1039896 OFFLINE sys@UTF8A> select name ,checkpoint_change# from v$datafile ; NAME                                              CHECKPOINT_CHANGE#--------------------------------------------------------------------/u01/apps/oracle/oradata/utf8a/system01.dbf                   1041564/u01/apps/oracle/oradata/utf8a/sysaux01.dbf                   1041564/u01/apps/oracle/oradata/utf8a/undotbs01.dbf                  1041564/u01/apps/oracle/oradata/utf8a/users01.dbf                    1039896

记得修改前先备份所有的数据库文件。

BBED> set file 4       FILE#           4 BBED> p kcvfhckpstruct 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1039896，确认无误，只要修改scn为最新的1041564，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 x64 ，为little endian。

1039896=18de0f00

1041564=9ce40f00

直接修改即可。

BBED> set 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> sumCheck value for File 4, Block 1:current = 0x5f67, required = 0x65e3 BBED> sum applyCheck 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    1041564 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 recoveryORA-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

完成后记得逻辑导出所有用户数据，并且完善备份计划。

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