alter database add logfile thread 1 group 5 ('+DATA/idb/onlinelog/group5.log') size 256m;
alter database add logfile thread 2 group 6 ('+DATA/idb/onlinelog/group6.log') size 256m;
alter database add logfile thread 1 group 1 ('+DATA/idb/onlinelog/group1.log') size 256m
alter database add logfile thread 1 group 2 ('+DATA/idb/onlinelog/group2.log') size 256m
alter database add logfile thread 2 group 3 ('+DATA/idb/onlinelog/group3.log') size 256m
alter database add logfile thread 2 group 4 ('+DATA/idb/onlinelog/group4.log') size 256m
alter database drop logfile group 3;
alter database drop logfile group 1;
alter database drop logfile group 2;
alter database drop logfile group 4;
alter system switch logfile;
select GROUP#,MEMBER from v$logfile;
select GROUP#,THREAD#,STATUS ,ARCHIVED from v$log;
prompt 查看日志文件
col member format a50;
select f.member "member", f.group# "group", l.bytes/1024/1024 "size", l.status from v$logfile f, v$log l
where f.group#=l.group# order by f.group#,f.member;