当logfile的一个group里面有多个member的时候，如果丢失一个member，oracle的文档说数据库可以正常工作：
If a disk that contains an online redo log file fails, other copies
are still intact and available to Oracle. System operation is not
interrupted and the lost online redo log files can be easily
recovered.
我们来做一个实验，先看看当前的数据库：
SQL> select member from v$logfile; MEMBER -------------------------------------------------------------------------------- /home/oracle/dingjia/guangxi/redo01.log /home/oracle/dingjia/guangxi/redo02.log /home/oracle/dingjia/guangxi/redo03.log SQL> select group#,members,status,sum(bytes/1024/1024) from v$log group by group#,members,status; 2 GROUP# MEMBERS STATUS SUM(BYTES/1024/1024) ---------- ---------- ---------------- -------------------- 1 1 INACTIVE 2048 3 1 INACTIVE 2048 2 1 CURRENT 2048
有三个group的logfile，我们向第一个group里面增加一个member
SQL> alter database add logfile member '/home/oracle/dingjia/guangxi/redo11.log' to group 1; Database altered. SQL> select GROUP# ,STATUS , MEMBER from v$logfile; GROUP# STATUS MEMBER ---------- ------- ---------------------------------------- 1 /home/oracle/dingjia/guangxi/redo01.log 2 /home/oracle/dingjia/guangxi/redo02.log 3 /home/oracle/dingjia/guangxi/redo03.log 1 /home/oracle/dingjia/guangxi/redo11.log
然后我们通过 alter system switch logfile 将第一组logfile变成current，再删除其中一个logfile。
SQL> select group#,members,status,sum(bytes/1024/1024) from v$log group by group#,members,status 2 ; GROUP# MEMBERS STATUS SUM(BYTES/1024/1024) ---------- ---------- ---------------- -------------------- 3 1 INACTIVE 2048 2 1 INACTIVE 2048 1 2 CURRENT 2048 SQL> host rm /home/oracle/dingjia/guangxi/redo11.log
在oracle的警告日志里有提示 $ tail -n 50
/u01/app/oracle/diag/rdbms/guangxi/guangxi/trace/alert_guangxi.log Errors in file /u01/app/oracle/diag/rdbms/guangxi/guangxi/trace/guangxi_arc0_10972.trc: ORA-00313: open failed for members of log group 1 of thread 1 ORA-00312: online log 1 thread 1: '/home/oracle/dingjia/guangxi/redo11.log' ORA-27037: unable to obtain file status Linux-x86_64 Error: 2: No such file or directory
数据库仍然在正常运转，运行各种测试都不影响。
解决的办法就把有故障的log member删除
SQL> alter database drop logfile member '/home/oracle/dingjia/guangxi/redo11.log'; Database altered.
