Download starts delayed

[Lite]

Hello
I hosted sites that have heavy traffic , this sites use more than 2TB bandwidth per day
Now i use trial 2-CPU LiteSpeed License

But a serious problem , sometimes server don't accept new connection or accept it late ,


Server information :
Processor 2 x E5620 2.40Ghz HT
Memory 24GB DDR3 ECC Memory
Hard Drive 4 x 2TB SAS 7,200 RPM
Raid H700 Raid Controller with BBU - Raid 10

IO wait :

root@ [~]# iostat -x
Linux 2.6.32-279.9.1.el6.x86_64 10/14/2012      _x86_64_        (16 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.43    0.39    3.02    8.37    0.00   87.78

Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await  svctm  %util
sda             488.05    26.18  774.56    9.47 95965.97   280.25   122.76    43.33   55.26   1.18  92.19
sdb             381.67   160.30  653.17    5.51 81479.33  1325.98   125.71    32.48   49.32   1.24  81.84
dm-0              0.00     0.00    0.01    0.00     0.06     0.00     7.95     0.00   11.84   8.11   0.01
dm-1              0.00     0.00    0.42    0.79    18.94     6.33    20.86     0.05   42.67  15.56   1.88
dm-2              0.00     0.00    0.03    4.92     0.27    39.34     8.00     0.25   49.54  23.61  11.68
dm-3              0.00     0.00    0.02    0.00     1.26     0.01    67.89     0.00   44.77  26.06   0.05
dm-4              0.00     0.00    5.77   17.97   189.97   143.74    14.06     1.87   78.93   2.34   5.55
dm-5              0.00     0.00    0.53    7.54    10.74    60.31     8.80     1.13  139.75   3.04   2.45
dm-6              0.00     0.00 2315.83  169.42 177011.65  1355.38    71.77    22.24    8.92   0.40  99.30
dm-7              0.00     0.00    1.68    0.14   212.16     1.12   117.37     0.09   51.55  14.44   2.62

connection (Real time status) :

Http In	31KB	Http Out	103,030KB
Https In	0KB	Https Out	0KB
Max	122,880	Idle	86
Http Used	16,696	Http Free	106,184
Https Used	0	Https Free	40,960
In Processing	16,610	Req/Sec	62.1
Total Req	75,271	Total Cache Hits	0
Cache Hit Rate	0%	Cache Hits/Sec	0.0

Load is ok , i/o wait is ok , i think configuration is ok too
but i don't know why server don't accept new connection and this problem has caused connection time out or Download starts delayed

i attached number of connection screenshot and tuning configuration
please some one help me

[mistwang]

You need to check ip_conntrack limit, check output of 'dmesg', if the limit has been hit, you need to google it for solution.

Also, with your server, we recommend enabling "AIO" if you are serving tons of static files.

[NiteWave]

I noticed "Http Out: 103,030KB", this already reach or over the 1G bps NIC's capability. maybe a good example though: the bottle neck is at NIC, not litespeed or others.

[Lite]

I have 6 account on this server ( i use cPanel )
in account 1,2,4,5 download start fast
but in other account we get time out

what can i do ?

[Lite]

I'm really confused
download start in some account is very fast
but in some account is very late

The strange thing is , in accounts that have more connection than others , downloads start fast
!

[webizen]

is the download via php or direct static?