1、多元化成员中，单个组成员丢失（当前组和非当前组的都一样，不会影响到数据库的正常运行）
解决方法：复制一下就行
05:10:06 SQL> select * from v$log;
GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- ---------
1          1          9   10485760          2 NO  INACTIVE                384007 02-AUG-11
3          1          8   10485760          2 NO  INACTIVE                384005 02-AUG-11
2          1         10   10485760          2 NO  CURRENT                 385481 02-AUG-11
05:10:12 SQL> !
[oracle@oracle ~]$ ls /disk2/lx01/oradata/
control03.ctl  redo01a.log  redo02a.log  redo03a.log  redo04a.log  redo05a.log
[oracle@oracle ~]$ exit
exit
05:14:31 SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
05:14:41 SQL> !
[oracle@oracle ~]$ rm  /disk2/lx02/oradata/redo01a.log
[oracle@oracle ~]$ !sql
sqlplus '/as sysdba'
SQL*Plus: Release 10.2.0.1.0 - Production on Tue Aug 2 05:15:02 2011
Copyright (c) 1982, 2005, Oracle.  All rights reserved.
Connected to an idle instance.
05:15:02 SQL> startup
ORACLE instance started.
Total System Global Area  251658240 bytes
Fixed Size                  1218820 bytes
Variable Size             125830908 bytes
Database Buffers          121634816 bytes
Redo Buffers                2973696 bytes
Database mounted.
Database opened.
05:15:12 SQL> select * from v$log;
GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- ---------
1          1          9   10485760          2 NO  INACTIVE                384007 02-AUG-11
3          1          8   10485760          2 NO  INACTIVE                384005 02-AUG-11
2          1         10   10485760          2 NO  CURRENT                 385481 02-AUG-11
05:15:24 SQL> desc v$logfile;
Name                                                                                Null?    Type
----------------------------------------------------------------------------------- -------- --------------------------------------------------------
GROUP#                                                                                       NUMBER
STATUS                                                                                       VARCHAR2(7)
TYPE                                                                                         VARCHAR2(7)
MEMBER                                                                                       VARCHAR2(513)
IS_RECOVERY_DEST_FILE                                                                        VARCHAR2(3）
05:15:43 SQL> col member for a50
05:15:48 SQL> r
1* select group#,member ,status from v$logfile
GROUP# MEMBER                                             STATUS
---------- -------------------------------------------------- -------
2 /disk2/lx02/oradata/redo02a.log
1 /disk2/lx02/oradata/redo01a.log                    INVALID
3 /disk2/lx02/oradata/redo03a.log
1 /disk1/lx02/oradata/redo01b.log
2 /disk1/lx02/oradata/redo02b.log
3 /disk1/lx02/oradata/redo03b.log
6 rows selected.
05:15:48 SQL>
告警日志：
Errors in file /u01/app/oracle/admin/lx02/bdump/lx02_lgwr_9105.trc:
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: '/disk2/lx02/oradata/redo01a.log'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
解决：
05:15:48 SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
05:17:47 SQL> !
[oracle@oracle ~]$ cp /disk1/lx02/oradata/redo01b.log /disk2/lx02/oradata/redo01a.log
[oracle@oracle ~]$ !sql
sqlplus '/as sysdba'
SQL*Plus: Release 10.2.0.1.0 - Production on Tue Aug 2 05:18:02 2011
Copyright (c) 1982, 2005, Oracle.  All rights reserved.
Connected to an idle instance.
05:18:02 SQL> startup
ORACLE instance started.
Total System Global Area  251658240 bytes
Fixed Size                  1218820 bytes
Variable Size             125830908 bytes
Database Buffers          121634816 bytes
Redo Buffers                2973696 bytes
Database mounted.
Database opened.
05:18:14 SQL> col member for a50
05:18:26 SQL> select group#,member ,status from v$logfile
05:18:29   2  ;
GROUP# MEMBER                                             STATUS
---------- -------------------------------------------------- -------
2 /disk2/lx02/oradata/redo02a.log
1 /disk2/lx02/oradata/redo01a.log                    INVALID
3 /disk2/lx02/oradata/redo03a.log
1 /disk1/lx02/oradata/redo01b.log
2 /disk1/lx02/oradata/redo02b.log
3 /disk1/lx02/oradata/redo03b.log
6 rows selected.
05:18:31 SQL> alter system switch logfile;
System altered.
05:18:37 SQL> /
System altered.
05:18:39 SQL> select group#,member ,status from v$logfile
05:18:40   2  ;
GROUP# MEMBER                                             STATUS
---------- -------------------------------------------------- -------
2 /disk2/lx02/oradata/redo02a.log
1 /disk2/lx02/oradata/redo01a.log
3 /disk2/lx02/oradata/redo03a.log
1 /disk1/lx02/oradata/redo01b.log
2 /disk1/lx02/oradata/redo02b.log
3 /disk1/lx02/oradata/redo03b.log
6 rows selected.