curren online redo损坏恢复一例

用户数据库不能打开，Alert log中报如下错误：
Fri Oct  3 20:02:27 2008
Errors in file /u01/oracle/admin/caq/bdump/caq_lgwr_2060404.trc:
ORA-00345: redo log write error block 152320 count 57
ORA-00312: online log 3 thread 1: '/u01/oracle/oradata/caq/redo03.log'
ORA-27063: skgfospo: number of bytes read/written is incorrect
IBM AIX RISC System/6000 Error: 110: Media surface error
Additional information: -1
Additional information: 29184
Fri Oct  3 20:02:28 2008
Errors in file /u01/oracle/admin/caq/bdump/caq_lgwr_2060404.trc:
ORA-00340: IO error processing online log 3 of thread 1
ORA-00345: redo log write error block 152320 count 57
ORA-00312: online log 3 thread 1: '/u01/oracle/oradata/caq/redo03.log'
ORA-27063: skgfospo: number of bytes read/written is incorrect
IBM AIX RISC System/6000 Error: 110: Media surface error
Additional information: -1
Additional information: 29184
LGWR: terminating instance due to error 340
Fri Oct  3 20:02:28 2008
Errors in file /u01/oracle/admin/caq/bdump/caq_pmon_2068688.trc:
ORA-00340: IO error processing online log  of thread
Fri Oct  3 20:02:29 2008
Errors in file /u01/oracle/admin/caq/bdump/caq_dbw0_2097222.trc:
ORA-00340: IO error processing online log  of thread
Fri Oct  3 20:02:30 2008
Errors in file /u01/oracle/admin/caq/bdump/caq_ckpt_2031842.trc:
ORA-00340: IO error processing online log  of thread
Fri Oct  3 20:02:38 2008
Instance terminated by LGWR, pid = 2060404

问题诊断：redo online log损坏，并且确认是current状态的redo log.

解决过程:
1. 启动数据库到mount状态下，从spfile文件创建pfile文件
Create pfile=’/u01/oracle/pfile.ora’ from spfile;
2. 因为online redo log所在的Disk中有坏块，所以不能简单的设置_ALL_RESETLOGS_CORRUPTION=TRUE然后resetlogs打开数据库就ok了，需要重建控制文件将redo log reset到其它完好的Disk上，然后resetlogs打开数据库。（这里重建控制文件主要是将日志重建到阵列上，原来是放在本地磁盘的rootvg中，rootvg并没有做镜像。）
（可能不需要重建控制文件）
Tue Oct  7 01:36:19 2008
RESETLOGS is being done without consistancy checks. This may result
in a corrupted database. The database should be recreated.
RESETLOGS after incomplete recovery UNTIL CHANGE 5687982655
Resetting resetlogs activation ID 629466185 (0x2584e449)
Online log 1 of thread 1 was previously cleared
Online log 2 of thread 1 was previously cleared
Tue Oct  7 01:36:19 2008
Errors in file /u01/oracle/admin/caq/udump/caq_ora_2011302.trc:
ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: '/u01/oracle/oradata/caq/redo03.log'
ORA-27037: unable to obtain file status
IBM AIX RISC System/6000 Error: 2: No such file or directory
Additional information: 3
/* 以上错误消息说明redo03.log没有找到，但是下面的消息似乎说明redo03.log应该是重建成功了!
*/
Tue Oct  7 01:36:24 2008
Assigning activation ID 629419807 (0x25842f1f)
Thread 1 opened at log sequence 1
Current log# 3 seq# 1 mem# 0: /u01/oracle/oradata/caq/redo03.log
Successful open of redo thread 1.
Tue Oct  7 01:36:25 2008
SMON: enabling cache recovery
/* 如果redo03.log文件重建成功，那么不能resetlogs打开数据库的本质原因应该是下面的错误导致的
*/
Tue Oct  7 01:36:25 2008
Errors in file /u01/oracle/admin/caq/udump/caq_ora_2011302.trc:
ORA-00600: internal error code, arguments: [2662], [1], [1393015364], [1], [1393016039], [8388617], [], []
Tue Oct  7 01:36:26 2008
Errors in file /u01/oracle/admin/caq/udump/caq_ora_2011302.trc:
ORA-00600: internal error code, arguments: [2662], [1], [1393015364], [1], [1393016039], [8388617], [], []
Tue Oct  7 01:36:26 2008
Error 600 happened during db open, shutting down database
USER: terminating instance due to error 600
/*
看来错误确实是ORA-600[2662]引起来的，后面的重建控制文件的步骤是多余的了，nnd
*/
Tue Oct  7 01:36:27 2008
Errors in file /u01/oracle/admin/caq/bdump/caq_pmon_2215976.trc:
ORA-00600: internal error code, arguments: [], [], [], [], [], [], [], []
Tue Oct  7 01:36:28 2008
Errors in file /u01/oracle/admin/caq/bdump/caq_dbw0_2080998.trc:
ORA-00600: internal error code, arguments: [], [], [], [], [], [], [], []
Tue Oct  7 01:36:28 2008
Errors in file /u01/oracle/admin/caq/bdump/caq_lgwr_2121866.trc:
ORA-00600: internal error code, arguments: [], [], [], [], [], [], [], []
Tue Oct  7 01:36:36 2008
Instance terminated by USER, pid = 2011302
ORA-1092 signalled during: alter database open resetlogs...
Tue Oct  7 01:41:34 2008
USER: terminating instance due to error 1092
Instance terminated by USER, pid = 2011302
Tue Oct  7 01:41:34 2008
Errors in file /u01/oracle/admin/caq/udump/caq_ora_2011302.trc:
ORA-27302: failure occurred at: skgpwreset1
ORA-27303: additional information: invalid shared ctx
ORA-01092: ORACLE instance terminated. Disconnection forced
ORA-00600: internal error code, arguments: [2662], [1], [1393015364], [1], [1393016039], [8388617], [], []

先解决ORA-600[2662]错误，metalink 28929.1 说是数据块的SCN大于数据库当前的SCN（A data block SCN is ahead of the current SCN）。
可以通过ORACLE内部事件ADJUST_SCN来增加当前的SCN值：
alter session set events '10015 trace name adjust_scn level 10'; --增加10 billion

重新打开数据库，这时数据库改报ORA-600[4193]错误了：
Tue Oct  7 02:07:09 2008
Errors in file /u01/oracle/admin/caq/bdump/caq_smon_2027644.trc:
ORA-01595: error freeing extent (3) of rollback segment (1))
ORA-00607: Internal error occurred while making a change to a data block
ORA-00600: internal error code, arguments: [4193], [6438], [6448], [], [], [], [], []

这是redo record与undo record不一致造成的。新建一个undo tablespace替换掉旧的undo即可！
参考metalink 39282.1

create undo tablespace undotbs2
datafile '/oracaq/oradata/caq/undotbs02.dbf' size 60M

由于数据库是使用pfile文件启动的，所以需要关闭数据库，设置undo_tablespace = UNDOTBS2，顺便把_ALL_RESETLOGS_CORRUPTION=TRUE去掉！启动数据库，新建database的默认临时表空间，然后执行数据库的完全导出，用导出的dmp文件新建数据库。