1.查询当前日志组及状态：

10:45:14 SYS@ORA11GR2>select group#,member from v$logfile;    GROUP# MEMBER---------- --------------------------------------------------         3 /u01/app/oracle/oradata/ORA11GR2/redo03.log         2 /u01/app/oracle/oradata/ORA11GR2/redo02.log         1 /u01/app/oracle/oradata/ORA11GR2/redo01.log         3 /u01/app/oracle/disk/redo03b.log         2 /u01/app/oracle/disk/redo02b.log         1 /u01/app/oracle/disk/redo01b.log6 rows selected.10:45:26 SYS@ORA11GR2>select group#,members,bytes/1024/1024 M,status from v$log;    GROUP#    MEMBERS          M STATUS---------- ---------- ---------- ----------------         1          2         50 CURRENT         2          2         50 INACTIVE         3          2         50 ACTIVE

2.模拟故障（正常关库删除一组当前日志组）：

10:45:53 SYS@ORA11GR2>shutdown immediateDatabase closed.Database dismounted.ORACLE instance shut down.[oracle@host03 ~]$ rm /u01/app/oracle/oradata/ORA11GR2/redo01.log[oracle@host03 ~]$ rm /u01/app/oracle/disk/redo01b.log

3.起库报错，查看alert日志：

ORA-00313: open failed for members of log group 1 of thread 1ORA-00312: online log 1 thread 1: '/u01/app/oracle/disk/redo01b.log'ORA-27037: unable to obtain file statusLinux-x86_64 Error: 2: No such file or directoryAdditional information: 3ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/ORA11GR2/redo01.log'ORA-27037: unable to obtain file statusLinux-x86_64 Error: 2: No such file or directoryAdditional information: 3

4.解决：将数据库起到mount

10:50:09 SYS@ORA11GR2>alter database clear logfile group 1;Database altered. 10:51:35 SYS@ORA11GR2>select group#,members,bytes/1024/1024 M,status from v$log;    GROUP#    MEMBERS          M STATUS---------- ---------- ---------- ----------------         1          2         50 UNUSED         3          2         50 INACTIVE         2          2         50 CURRENT10:51:41 SYS@ORA11GR2>alter database open;Database altered.