实验环境：
OEL5.6 Oracle11.2.0.1
实验开始：
数据库运行状态，删除所有日志：
[oracle@ITAA TEST]$ ls
control01.ctl redo01.log sysaux01.dbf undotbs01.dbf
data_ol01.dbf redo02.log system01.dbf users01.dbf
example01.dbf redo03.log temp01.dbf
[oracle@ITAA TEST]$ rm -rf *.log
在数据库中切换日志组：
SYS@TEST>alter system switch logfile;
?
System altered.
?
SYS@TEST>/
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System altered.
?
SYS@TEST>/
?
?
alter system switch logfile
*
ERROR at line 1:
ORA-01013: user requested cancel of current operation
?
?
?
SYS@TEST>insert into t select * from dba_objects;
?
72504 rows created.
?
SYS@TEST>/
?
72504 rows created.
?
SYS@TEST>/
?
72504 rows created.
?
SYS@TEST>/
?
72504 rows created.
?
SYS@TEST>/
?
72504 rows created.
?
SYS@TEST>/
此时数据库hung住，所有业务都暂停，alert日志报错如下：
Mon Jul 13 17:03:28 2015
Errors in file /u01/app/oracle/diag/rdbms/test/TEST/trace/TEST_m000_23367.trc:
ORA-00313: open failed for members of log group 1 of thread 1
ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/TEST/redo01.log'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
Errors in file /u01/app/oracle/diag/rdbms/test/TEST/trace/TEST_m000_23367.trc:
ORA-00313: open failed for members of log group 2 of thread 1
ORA-00312: online log 2 thread 1: '/u01/app/oracle/oradata/TEST/redo02.log'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
Errors in file /u01/app/oracle/diag/rdbms/test/TEST/trace/TEST_m000_23367.trc:
ORA-00313: open failed for members of log group 3 of thread 1
ORA-00312: online log 3 thread 1: '/u01/app/oracle/oradata/TEST/redo03.log'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
?
暂时关闭监听，防止新业务占满session，此时新连接可以正常连入数据库。
这时候不要停库，因为数据库已经无法正常关闭，一旦数据库down掉，必然会丢失数据。
此时使用sysdba连入数据库，直接clear日志组，数据库即可恢复正常运行。
SYS@TEST>alter database clear unarchived logfile group 1;
?
?
Database altered.
?
SYS@TEST>alter database clear unarchived logfile group 2;
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Database altered.
?
SYS@TEST>alter database clear unarchived logfile group 3;
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Database altered.
数据库运行恢复正常。