由于数据库目前的redo配置为1G，从日志上看，redo切换过于频繁，而且不能及时归档。这个表象会很大程度影响数据库性能，所以进行如下调优
1：sqlplus / as sysdba
添加如下8组redo
alter database add logfile thread 1 group 9 ('+DATA1/xxzxdb/NLINELOG/group9a','+DATA1/xxzxdb/NLINELOG/group9b') size 2000M;
alter database add logfile thread 2 group 10 ('+DATA1/xxzxdb/NLINELOG/group10a','+DATA1/xxzxdb/NLINELOG/group10b') size 2000M;
alter database add logfile thread 1 group 11 ('+DATA1/xxzxdb/NLINELOG/group11a','+DATA1/xxzxdb/NLINELOG/group11b') size 2000M;
alter database add logfile thread 2 group 12 ('+DATA1/xxzxdb/NLINELOG/group12a','+DATA1/xxzxdb/NLINELOG/group12b') size 2000M;
alter database add logfile thread 1 group 13 ('+DATA1/xxzxdb/NLINELOG/group13a','+DATA1/xxzxdb/NLINELOG/group13b') size 2000M;
alter database add logfile thread 2 group 14 ('+DATA1/xxzxdb/NLINELOG/group14a','+DATA1/xxzxdb/NLINELOG/group14b') size 2000M;
alter database add logfile thread 1 group 15 ('+DATA1/xxzxdb/NLINELOG/group15a','+DATA1/xxzxdb/NLINELOG/group15b') size 2000M;
alter database add logfile thread 2 group 16 ('+DATA1/xxzxdb/NLINELOG/group16a','+DATA1/xxzxdb/NLINELOG/group16b') size 2000M;
2：添加之后，执行alter system switch logfile;--多执行几次。切换redo ，一直切换到新加的9这里来，让9变成current
select a.members,
a.thread#,
a.status,
a.bytes / 1024 / 1024,
b.type,
b.member,
b.group#
from v$log a, v$logfile b
where a.group# = b.group#;
3：当redo group 1-8 的状态变成“INACTIVE”就可以进行删除
SQL> alter database drop logfile group 1;
Database altered
4：当1-8组日志，还是处于active状态，没有归档完成，这个时候是不能删除的，
执行 sql>alter system checkpoint;
这样就会将1-8组的日志逐个删除即可。
