最近由于机房停电事件，导致数据库主机异常关闭，主机恢复正常后，启动数据库报错：
ORA-00600: internal error code, arguments: [kcratr_nab_less_than_odr], [1], [8120], [21090], [21205], [], [], [], [], [], [], []
查看alert日志，错误如下：
...省略...
ALTER DATABASE OPEN #在open阶段报错了
Beginning crash recovery of 1 threads #在进行crash recovery
parallel recovery started with 2 processes
Started redo scan
Completed redo scan
read 2095 KB redo, 98 data blocks need recovery
Errors in file /opt/oracle/diag/rdbms/stgorcl/stgorcl/trace/stgorcl_ora_22775.trc (incident=89339):
ORA-00600: internal error code, arguments: [kcratr_nab_less_than_odr], [1], [8120], [21090], [21205], [], [], [], [], [], [], []
Incident details in: /opt/oracle/diag/rdbms/stgorcl/stgorcl/incident/incdir_89339/stgorcl_ora_22775_i89339.trc
...省略...
联系主机异常关闭事件，推测可能由于主机异常关闭引起数据库文件被损坏，结合数据库的报错信息看，怀疑是controlfile损坏了。
通过 kcratr_nab_less_than_odr 关键字，在MOS找一篇与此实际相符的文档Alter database open fails with ORA-00600 kcratr_nab_less_than_odr (文档 ID 1296264.1)，对比文档与/opt/oracle/diag/rdbms/stgorcl/stgorcl/incident/incdir_89339/stgorcl_ora_22775_i89339.trc 的 "Call Stack Trace"，基本确认该事件与文档描述的一致。
----- Call Stack Trace -----
ksedst1 <- ksedst <- dbkedDefDump <- ksedmp <- dbgexPhaseII <- dbgexProcessError <- dbgePostErrorKGE <- kgeasnmierr <- kcratr_odr_check <- kcratr <- kctrec <- kcvcrv <- kcfopd <- adbdrv <- opiexe <- opiosq0 <- kpoal8 <- opiodr <- ttcpip <- opitsk <- opiino <- opiodr <- opidrv <- sou2o <- opimai_real <- ssthrdmain <- main <- start
该故障是由于停电故障导致控制文件逻辑corruption造成，文档給出2个解决方案：
Option a: Do cancel based reocvery, and apply 'current online redolog' manually #做recover using backup controlfile
Option b: Recreate the controlfile using the Controlfile recreation script #重建控制文件
方案a更简单，采用方案a：
找到CURRENT redo,做recover需要用到这个文件。
sys@STGORCL> select a.member, a.group#, b.status from v$logfile a ,v$log b where a.group#=b.group#;
MEMBER GROUP# STATUS
---------------------------------------- ---------- ------------------------------------------------
/opt/oracle/oradata/stgorcl/redo03.log 3 INACTIVE
/opt/oracle/oradata/stgorcl/redo02.log 2 CURRENT
/opt/oracle/oradata/stgorcl/redo01.log 1 INACTIVE
SQL> recover database using backup controlfile until cancel ;
ORA-00279: change 140911009 generated at 04/24/2016 16:12:46 needed for thread
1
ORA-00289: suggestion :
/opt/oracle/product/11.2.0/db_1/dbs/arch2_8120_857011473.dbf #该redo实际未归档，对应的是/opt/oracle/oradata/stgorcl/redo02.log
ORA-00280: change 140911009 for thread 1 is in sequence #8120
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
/opt/oracle/oradata/stgorcl/redo02.log
Log applied.
Media recovery complete.
最后使用resetlogs打开数据库
SQL> alter database open resetlogs;
Database altered.
注：resetlogs后，需要重新备份，重新搭建DG
