[Tfug] Need help on a server performance issue...

[Angus Scott-Fleming]

26 Sep 2010 at 17:01, Jim March  wrote:

> The Ethernet ports in the servers and workstations are 100mb grade.
> The router is a good one, definitely 100 or better (small Sonicwall).
> Ditto one hub (lots of printers and other junk around).
> 
> So...I'm thinking I need to see if the Ethernet port in the server is
> going south, OR check for something on the local net dumping excess
> packets.  Been years since I've had to wrassle with something like
> this.  Do I use Wireshark or the like to check for something screwy?

With as few computers as you have, I would consider a brute-force, simple 
troubleshooting technique:  Test A: disconnect everything from the server, 
connect one computer to the server with a crossover cable and try copying over 
that. If Test A is slow, try copying from that computer to another the same way 
(Test B) to see if the slow NIC is in the server or in the computer.  If A and 
B are both slow, test computer B to the server.  You should be able to tell 
from A and B where the bottleneck for Test A is.

If Test A is fast, then the server NIC is OK.  Now try to copy through the 
switch to the same computer.  As long as that is fast, add the other computers 
back one at a time, testing after each addition.  When the copying gets slow, 
unplug the last computer and test again -- there's your bad NIC or bad port in 
the switch or bad duplex mismatch or bottleneck.

I might try to talk the client into picking up one of these:

    HP ProCurve Switch 1810G Series J9450A, J9449A 
    http://h10144.www1.hp.com/products/switches/HP_ProCurve_1810G_Switch_Series/overview.htm#J9449A

8-port managed switch -- allows you through a web interface to monitor 
throughput on each port.  Really helps when trying to track down network 
performance bottlenecks, plus since it's managed you can control the speed and 
duplex settings on a port-by-port basis.  If you have to spend >$200 in your 
time isolating the problem, spending $150 on a switch like this will pay itself 
back quickly.  If you need >14 ports (8+8-2 for the link between the switches), 
the 24-port version is a better deal per-port than 2 of them.

    Newegg.com - HP J9449A#ABA 10/100/1000Mbps ProCurve Switch 8 x RJ45 8,000 
    entries MAC Address Table 8 MB flash, 16 MB SDRAM; packet buffer size: 512 
    KB Buffer Memory 
    http://www.newegg.com/Product/Product.aspx?Item=N82E16833316155

    PROVANTAGE: Hewlett Packard HP J9449A#ABA ProCurve Switch 1810G-8 8-
    10/100/1000 Ports  
    http://www.provantage.com/hewlett-packard-hp-j9449a-aba~7HPP951V.htm

HP also has some 16-port managed switches, I think the 2510 is around $200.

HTH

--
Angus Scott-Fleming
GeoApps, Tucson, Arizona
1-520-290-5038
Security Blog: http://geoapps.com/