SQL> ALTER DATABASE CLEAR logfile group 3;

SQL> SELECT group#, sequence#, members, bytes, status, archived FROM v$log;

SQL> SELECT * FROM v$logfile;

SQL> alter system set DB_CREATE_ONLINE_LOG_DEST_1 = '/home/oracle/disk3';

SQL> alter system set DB_CREATE_ONLINE_LOG_DEST_2 = '/home/oracle/disk6';

SQL> alter system set DB_CREATE_ONLINE_LOG_DEST_3 = '/home/oracle/disk9';

SQL> alter database add logfile;

SQL> alter database drop logfile group 4;

SQL> alter database add logfile ( '/home/oracle/disk3/huang/onlinelog/redo04a.log', '/home/oracle/disk6/huang/onlinelog/redo04b.log', '/home/oracle/disk9/huang/onlinelog/redo04c.log') SIZE 15M;

SQL> alter database add logfile ( '/home/oracle/disk3/huang/onlinelog/redo05a.log', '/home/oracle/disk6/huang/onlinelog/redo05b.log', '/home/oracle/disk9/huang/onlinelog/redo05c.log') SIZE 15M;

SQL> alter database drop logfile group 3;

SQL> alter database add logfile ( '/home/oracle/disk3/huang/onlinelog/redo03a.log', '/home/oracle/disk6/huang/onlinelog/redo03b.log', '/home/oracle/disk9/huang/onlinelog/redo03c.log') SIZE 15M;

SQL> alter database drop logfile group 2;

SQL> alter database add logfile ( '/home/oracle/disk3/huang/onlinelog/redo02a.log', '/home/oracle/disk6/huang/onlinelog/redo02b.log', '/home/oracle/disk9/huang/onlinelog/redo02c.log') SIZE 15M;

SQL> alter system switch logfile;
若第一组的状态(status)还是ACTIVE,再次执行下面命令,直到其状态为INACTIVE
SQL> alter system switch logfile;

SQL> alter database drop logfile group 1;

SQL> alter database add logfile ( '/home/oracle/disk3/huang/onlinelog/redo01a.log', '/home/oracle/disk6/huang/onlinelog/redo01b.log', '/home/oracle/disk9/huang/onlinelog/redo01c.log') SIZE 15M;