对每个redo日志组增加一个成员，同时修改每个成员的大小为800M。
1、查询当前日志组情况
SQL> SELECT group#, members, bytes/1024/1024 byte_mb, status FROM v$log; GROUP# MEMBERS BYTE_MB STATUS ---------- ---------- ---------- ---------------- 1 1 50 ACTIVE 2 1 50 ACTIVE 3 1 50 CURRENT
三组，每组一个成员
2、新增日志组4/5/6，每组2个成员
alter database add logfile group 4 ('/data/oradata/orclwhs/redo04.log','/home/oracle/app/oracle/oradata/orclwhs/redo04.log') size 800M; alter database add logfile group 5 ('/data/oradata/orclwhs/redo05.log','/home/oracle/app/oracle/oradata/orclwhs/redo05.log') size 800M; alter database add logfile group 6 ('/data/oradata/orclwhs/redo06.log','/home/oracle/app/oracle/oradata/orclwhs/redo06.log') size 800M;
3、切换redo至4,5,6上（CURRENT在4,5,6上）
alter system switch logfile;
4、改变检查点，激发脏块写入磁盘，redo切换为INACTIVC
alter system checkpoint;
5、删除INACTIVE日志组
alter database drop logfile group 1; alter database drop logfile group 2; alter database drop logfile group 3;