shutdown abort模式丢失redo，使用隐含參数启库

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 从该错误能够看出当前日志的redo block的header出现故障，导致oracle无法读取redo进行恢复。通过下面检查发现数据库文件头都一致。没有须要恢复的文件，可是因为数据库是非正常关闭。last_change scn没有被写入，数据库推断须要恢复。则读取对应的redo log group 3。可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: '/opt/oracle/oradata/orcl11g/redo03.log'
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: {<RET>=suggested | filename | AUTO | CANCEL}

ORA-00308: cannot open archived log '/opt/oracle/flash_recovery_area/ORCL11G/archivelog/2014_10_29/o1_mf_1_159_%u_.arc'
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: '/opt/oracle/oradata/orcl11g/system01.dbf'

增加下面隐含參数：
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能够打开的

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