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，
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: {=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....
因为是这里为linux x64 ，为little endian。
1039896=18de0f00
1041564=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 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 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。