shutdownabort模式丢失redo，使用隐含参数启库

shutdown abort模式 丢失redo log 无法open数据库 通过告警报错ORA-00354: corrupt redo log block header 从该错误可以看出当前日志的redo block的header出现问题，导致oracle无法读取redo进行恢复。通过以下检查发现数据库文件头都一致，没有需要恢复的文件

shutdown abort模式
丢失redo log
无法open数据库
通过告警报错ORA-00354: corrupt redo log block header 从该错误可以看出当前日志的redo block的header出现问题，导致oracle无法读取redo进行恢复。通过以下检查发现数据库文件头都一致，没有需要恢复的文件，但是由于数据库是非正常关闭，last_change scn没有被写入，数据库判断需要恢复，则读取相应的redo log group 3，但是此时该文件已经损坏。

SYS@orcl11g>alter database open resetlogs;
alter database open resetlogs
*
ERROR at line 1:
ORA-01139: RESETLOGS option only valid after an incomplete database recovery

SYS@orcl11g>recover database;
ORA-00283: recovery session canceled due to errors
ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: &＃39;/opt/oracle/oradata/orcl11g/redo03.log&＃39;
ORA-27046: file size is not a multiple of logical block size
Additional information: 1

SYS@orcl11g>recover database until cancel;
ORA-00279: change 5168496 generated at 10/29/2014 23:48:23 needed for thread 1
ORA-00289: suggestion : /opt/oracle/flash_recovery_area/ORCL11G/archivelog/2014_10_29/o1_mf_1_159_%u_.arc
ORA-00280: change 5168496 for thread 1 is in sequence #159

Specify log: {=suggested | filename | AUTO | CANCEL}

ORA-00308: cannot open archived log &＃39;/opt/oracle/flash_recovery_area/ORCL11G/archivelog/2014_10_29/o1_mf_1_159_%u_.arc&＃39;
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: &＃39;/opt/oracle/oradata/orcl11g/system01.dbf&＃39;

加入以下隐含参数：
SYS@orcl11g>show parameter _allow
NAME                                 TYPE                   VALUE
------------------------------------ ---------------------- ------------------------------
_allow_error_simulation              boolean                TRUE
_allow_resetlogs_corruption          boolean                TRUE

这时候发现数据库时可以打开的

SYS@orcl11g>
SYS@orcl11g>
SYS@orcl11g>alter database open resetlogs;

Database altered.

SYS@orcl11g>

发现日志文件已经被重建：
SYS@orcl11g>select group#,status from v$log;
    GROUP# STATUS
---------- ------------------------------------------------------------
         1 CURRENT
         2 UNUSED
         3 UNUSED

SYS@orcl11g>alter system switch logfile;

System altered.

SYS@orcl11g>/

System altered.

SYS@orcl11g>/

System altered.

SYS@orcl11g>select group#,status from v$log;
    GROUP# STATUS
---------- ------------------------------------------------------------
         1 CURRENT
         2 INACTIVE
         3 ACTIVE