Extreme Slowdown using Gb Network

Seumas Macmhicean seumas at realise.com
Tue Mar 25 10:16:01 CST 2003

I'll reply to a couple of responses at once - thanks all for promptness!

>You said that "all other boxes on the network experience a crippling
>slowdown" when copying large files.  Do you mean that Box C is slow
>delivering data to the public network when Box A is copying files to Box
>B on the private Gb network?  Or is Box C slow in talking to Box D on
>the private network when the transfers are happening?

To clarify - when copying largish files between boxes A and B, all other
boxes become
very unresponsive in general usage - reports on CPU, disk, network and so on
all appear normal.
Nothing appears in dmesg nor messages, but the other boxes chug - even doing
a simple 'ls'.

>What do the network traffic lights look like on both switches?

It's in the Co Location facility... will have to check another day

>Is there anything strange in the output of sar -n eth[01]? on both the
>transfering and non-transfering systems?

We're going to investigate this.

>You could be having problems with the nics advertised auto-negotiating and
having problems with renegotiating
>during a heavy network load.

We're looking at ethtool but it seems to break the interface - we'll keep at
it and see if we can switch off the autonegotiation since we don't need it
(all devices on the network are the same - tg3)

>This may sound like an obvious step, but have you verified that you are
using cat5E and not cat5 on these?

Interesting point - the cables were bought new for this build and are about
2 months old - will have to check them explicitly (again - Co-Location
facility) but aren't they all Cat5e compatible nowadays? Still, something to

>Which model switch?

NetGear GS516T - bog standard config-free Gb switch

>Possibly, but any modern network switch acts as a multi-port bridge, so
>your other boxes should not even see traffic. 

Of course... but the effect is there - we'll do some more thorough checks to
make sure though... Hmmm. Faulty switch?

Something very odd is afoot here...


This electronic message contains information which may be privileged and
confidential.  The information is intended to be for the use of the
individual(s) or entity named above.  If you are not the intended recipient,
be aware that any disclosure, copying, distribution or use of the contents
of this information is prohibited.  If you have received this electronic
message in error, please notify us by telephone on 0131 476 6000 and delete
the material from your computer.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.us.dell.com/pipermail/linux-poweredge/attachments/20030325/e20e1cb4/attachment.htm

More information about the Linux-PowerEdge mailing list