求助：oracle数据库服务器wa值较高！

op - 09:38:22 up 2 days, 22 min,  1 user,  load average: 5.88, 6.01, 5.86
Tasks: 165 total,   1 running, 163 sleeping,   0 stopped,   1 zombie
Cpu0  :  6.4% us,  0.3% sy,  0.0% ni, 86.1% id,  7.1% wa,  0.0% hi,  0.0% si
Cpu1  :  7.1% us,  0.3% sy,  0.0% ni, 55.7% id, 36.8% wa,  0.0% hi,  0.0% si
Cpu2  :  0.0% us,  0.0% sy,  0.0% ni, 70.7% id, 29.3% wa,  0.0% hi,  0.0% si
Cpu3  :  0.0% us,  0.0% sy,  0.0% ni, 99.7% id,  0.3% wa,  0.0% hi,  0.0% si
Cpu4  :  4.0% us,  0.7% sy,  0.0% ni, 39.2% id, 54.2% wa,  0.0% hi,  2.0% si
Cpu5  :  0.3% us,  0.3% sy,  0.0% ni, 91.9% id,  7.4% wa,  0.0% hi,  0.0% si
Cpu6  :  0.3% us,  0.0% sy,  0.0% ni, 93.6% id,  6.1% wa,  0.0% hi,  0.0% si
Cpu7  :  0.0% us,  0.0% sy,  0.0% ni, 100.0% id,  0.0% wa,  0.0% hi,  0.0% si
Mem:   4044904k total,  4028180k used,    16724k free,     5032k buffers
Swap:  4192956k total,   118172k used,  4074784k free,  3349740k cached  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                
18793 oracle    15   0 2820m 1.3g 1.3g S   14 33.5   4:24.60 oracle                                                                 
16243 oracle    15   0 2825m 2.4g 2.3g D    3 61.2 151:25.20 oracle                                                                 
19210 oracle    16   0 2815m 902m 896m S    1 22.8   0:02.46 oracle                                                                 
  121 root      15   0     0    0    0 S    0  0.0   5:31.88 kswapd0                                                                
 7064 oracle    15   0 2823m 2.3g 2.3g S    0 59.7   3:04.62 oracle                                                                 
 7066 oracle    15   0 2815m 2.3g 2.3g S    0 59.4   3:05.40 oracle                                                                 
 7068 oracle    16   0 2834m  32m  29m S    0  0.8   4:37.79 oracle                                                                 
 7080 oracle    16   0 2811m  49m  46m S    0  1.3   0:02.75 oracle                                                                 
18787 oracle    15   0 2813m 168m 162m S    0  4.3   0:05.15 oracle                                                                 
18797 oracle    15   0 2812m 217m 212m S    0  5.5   0:13.79 oracle                                                                 
19206 oracle    15   0 2813m 892m 887m D    0 22.6   0:02.41 oracle                                                                 
19304 oracle    16   0 2813m 892m 886m S    0 22.6   0:01.96 oracle                                                                 
    1 root      16   0  4752  552  460 S    0  0.0   0:01.27 init  不知是何原因，请高手赐教啊！