time out in one site , but other sites is ok

[Lite]

Hello
i have strange problem
i use litespeed for my download server
i hosted about 6host in my server
sites on one ip are ok , but sites on other ip have connection time out
here is i/o wait , seem ok

x86_64_ (16 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.41    0.36    3.05    8.92    0.00   87.25

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda             505.45     67617.52       774.03 11294389048  129289096
sdb             588.83     82499.84       354.71 13780235242   59248728
dm-0              0.01         0.06         0.00       9976          0
dm-1             13.75        17.97       106.70    3001332   17821752
dm-2              4.67         0.25        37.10      42522    6197264
dm-3              0.02         1.16         0.00     194434        288
dm-4             22.09       102.10       158.47   17054730   26470584
dm-5             14.46         8.57       112.83    1431610   18846192
dm-6           1791.40    149773.57       713.22 25017200482  119132040
dm-7              1.72       213.49         0.42   35659330      69944

the stranger issue is , heaviest site on server is ok , but some other have a serious problem and get down 13h per day ( connection time out )
heaviest site is ok when other site get down !!!

i attached real time state