[CentOS] centos server network speed check???

[Brian Mathis]

On Mon, Mar 28, 2011 at 5:13 PM, mcclnx mcc <mcclnx at yahoo.com.tw> wrote:
> we have several servers on same rack and servers are all inside firewall.  Centos version from 4.X to 5.X.  sometime the connection are very slow (compare to servers on other racks also inside firewall).
>
> we discuss with network engineer he ask us use "ping" and traceroute" to check.  Both tools response time are good but if we connect through application like Web browser, database, or DELL OPMN tool.  The response time is very very slow.
>
> This situation normally last 4 to 5 hours then it back to normal.  Does there has way to check "real" network response time so we can show to network engineer.  Otherwise they always say "no problem".
>
> Thanks.


If you run 'iperf' between the 2 servers you will be able to check the
bandwidth at that time.  It could be that you have another application
using all the bandwidth, or the network has slowed down for some other
reason.  you could also try using Cacti to monitor the bandwidth
through the switch.

Also install the sysstat package on all servers and let it run every
minute.  You can graph the data using ksar on your local system.  The
graphs may show you that something else is going on.

Check the crontabs as well.  Does the time window line up with when
you are running backups or something else over the network?

Ping an traceroute are going to be mostly useless for this problem.
They can help determine connectivity, but even a 56k modem can be
"connected" and pass.  Iperf will stress the bandwidth portion of the
equation.