咨询oracle 性能慢问题

环境：solaris + oracle 10.2+ocr+裸设备双机

用户说起单机oracle性能还可以，起了双机后性能很慢。
查看了oracle日志发现日志切换频繁是否是这个引起的。


  Current log# 1 seq# 30492 mem# 0: /dev/rdsk/c1t9d0s0
Fri Aug 13 19:09:10 2010
Thread 1 advanced to log sequence 30493
"alert_kms1.log" 3491 行，134770 字符
Thu Aug 19 10:36:10 2010
Thread 1 cannot allocate new log, sequence 30916
Checkpoint not complete
  Current log# 2 seq# 30915 mem# 0: /dev/rdsk/c1t9d0s1
Thread 1 advanced to log sequence 30916
  Current log# 1 seq# 30916 mem# 0: /dev/rdsk/c1t9d0s0
Thu Aug 19 10:38:00 2010
Thread 1 cannot allocate new log, sequence 30917
Checkpoint not complete
  Current log# 1 seq# 30916 mem# 0: /dev/rdsk/c1t9d0s0
Thread 1 advanced to log sequence 30917
  Current log# 2 seq# 30917 mem# 0: /dev/rdsk/c1t9d0s1
Thu Aug 19 10:40:01 2010
Thread 1 advanced to log sequence 30918
  Current log# 1 seq# 30918 mem# 0: /dev/rdsk/c1t9d0s0
Thu Aug 19 10:42:19 2010
Thread 1 cannot allocate new log, sequence 30919
Checkpoint not complete
  Current log# 1 seq# 30918 mem# 0: /dev/rdsk/c1t9d0s0
Thread 1 advanced to log sequence 30919
  Current log# 2 seq# 30919 mem# 0: /dev/rdsk/c1t9d0s1
Thu Aug 19 10:44:03 2010
Thread 1 cannot allocate new log, sequence 30920
Checkpoint not complete
  Current log# 2 seq# 30919 mem# 0: /dev/rdsk/c1t9d0s1
Thread 1 advanced to log sequence 30920
  Current log# 1 seq# 30920 mem# 0: /dev/rdsk/c1t9d0s0
Thu Aug 19 10:45:58 2010
Thread 1 advanced to log sequence 30921
  Current log# 2 seq# 30921 mem# 0: /dev/rdsk/c1t9d0s1
Thu Aug 19 10:56:14 2010
Thread 1 advanced to log sequence 30922
  Current log# 1 seq# 30922 mem# 0: /dev/rdsk/c1t9d0s0
Thu Aug 19 11:39:25 2010
Thread 1 advanced to log sequence 30923
  Current log# 2 seq# 30923 mem# 0: /dev/rdsk/c1t9d0s1
Thu Aug 19 11:42:10 2010
Thread 1 advanced to log sequence 30924
  Current log# 1 seq# 30924 mem# 0: /dev/rdsk/c1t9d0s0
Thu Aug 19 11:44:02 2010
Thread 1 advanced to log sequence 30925
  Current log# 2 seq# 30925 mem# 0: /dev/rdsk/c1t9d0s1
Thu Aug 19 11:45:17 2010
Thread 1 advanced to log sequence 30926
  Current log# 1 seq# 30926 mem# 0: /dev/rdsk/c1t9d0s0
Thu Aug 19 11:51:26 2010
Starting background process EMN0

查看redo都已经150M了。应该也不小了。
SQL> select * from  v$log;

    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
FIRST_CHANGE# FIRST_TIME
------------- --------------
         1          1      30928  157286400          1 YES INACTIVE
   6068761252 19-8月 -10

         2          1      30929  157286400          1 NO  CURRENT
   6068852336 19-8月 -10

         3          2      53503  157286400          1 YES INACTIVE
   6068813599 19-8月 -10


    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
FIRST_CHANGE# FIRST_TIME
------------- --------------
         4          2      53504  157286400          1 NO  CURRENT
   6068905921 19-8月 -10

SQL> select member from v$logfile;

MEMBER
--------------------------------------------------------------------------------
/dev/rdsk/c1t9d0s1
/dev/rdsk/c1t9d0s0
/dev/rdsk/c1t10d0s0
/dev/rdsk/c1t10d0s1


发现第一台设备切换用的是
/dev/rdsk/c1t9d0s1
/dev/rdsk/c1t9d0s0

发现第二台设备切换用的是
/dev/rdsk/c1t10d0s0
/dev/rdsk/c1t10d0s1

是否正常。