Slow Web Access failure

Today came to the company there are sales response to a lot of customer response site visit is very slow, and then hurried to their own visit to try, really slow surprisingly, so began to troubleshoot:

1. Check the basic performance of the system: memory, CPU, disk

Free-m viewing memory (no problem with memory)

Top View CPU load conditions (low load)

Df-h View disk (disk only 20%)

So it can be judged that it has nothing to do with basic system performance

2. View the status of TCP

Netstat-n | awk '/^tcp/{++s[$NF]} END {for (a in S) print A, s[a]} '

Time_wait 2671 close_wait fin_wait1 fin_wait2 2 established SYN_RECV 28 CLOSING Last_ack 15

Combined to see, although the value of time_wait is relatively high, but does not cause the site to visit very slow, can be excluded is here in addition to the problem

3, through the iftop to view the bandwidth used by the site

Discovering that the machine is now using much more bandwidth than we have purchased, so judging the problem is here, upgrading the bandwidth, problem solving

4, the main tool used in this fault is Iftop,iftop is Linux under the view of the real-time bandwidth of the machine tool, how to use it does not say, here is a description of the interface, I want to know specifically can go to man iftop!

Iftop Interface Related Instructions

The interface above shows a scale range similar to that of the scale, which is used as a ruler for the bar showing the flow graph.

The <= in the middle and the two left and right arrows indicate the direction of the flow.

TX: Send Traffic
RX: Receive Traffic
Total: Overall flow
Cumm: Total traffic running iftop to current time
Peak: Traffic Peaks
Rates: Represents the average traffic for the past 2s 10s 40s, respectively

This article is from the "Help God help!" "Blog, be sure to keep this provenance http://chenyicai.blog.51cto.com/1593876/1439603