于是呼、shutdown 掉实例后、open 实例竟然淘气地起不来

sys@ORACLE10> alter database open;
alter database open
*
ERROR at line 1:
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/oracle10/redo01.log'

       在这里、我们大概可知日志组1的日志文件损坏了
       查看 v$log 视图

sys@ORACLE10> select group#,sequence#,archived,status from v$log;

    GROUP#  SEQUENCE# ARC STATUS
---------- ---------- --- ----------------
         1          2 YES INACTIVE
         3          1 YES INACTIVE
         2          3 NO  CURRENT

       可以知道、改组是非当前状态、而且已经归档
       用 clear 命令重建该日志文件

sys@ORACLE10> alter database clear logfile group 1;

Database altered.

       如果该日志组还没有归档、则需要：
       alter database clear unarchived logfile group 1;
       
       打开数据库、然后建议重新备份数据库

sys@ORACLE10> alter database open;

Database altered.