网站一开启网站访问硬盘读取就变慢

未开启网站时的数据:

Timing buffered disk reads:  156 MB in  3.03 seconds =  51.47 MB/sec

 

开启网站后的数据:

Timing buffered disk reads:   18 MB in  3.11 seconds =   5.78 MB/sec

 

站点程序有那么大的文件写入和读取?