Re: Network speed degredation?

2003-04-01 Thread Michael O'Donnell 


Check out mii-tool - it might help.

You can use it to query the current MII settings
and to nail them where they should be if they aren't
right.  Sometimes two NICs fail to properly negotiate
their optimal settings and (say) a 100Mb-FD connection
might end up running at (say) 10Mb-HD.  Worth a try...

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Re: Network speed degredation?

2003-04-01 Thread Hewitt Tech 
Believe it or not, disk I/O bandwidth is often the culprit in situations
like this. Try moving the same amount of data from disk to disk and see what
happens. Make sure you invalidate the cache if you do this in a loop to
overcome the effects of extensive read caching.  I think you'll find that
your disks can't keep up with gigabit speed connections.

-Alex

P.S. You can run iostat to get an idea of how much data/how fast you can
actually write to drives.

- Original Message -
From: Ken D'Ambrosio [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Tuesday, April 01, 2003 4:51 PM
Subject: Network speed degredation?


Howdy, all.  I've got something that might be worth of April Fool's if it
weren't for the facts that
a) it's been happening for a while, and
b) it's really annoying.

Specifically, my NICs, in at least two of my machines, are going at
roughly 1/10th the speed they're spec'd for.  I fully understand that a
100Mbit NIC will never actually see 100 Mbit -- more like 80.  And for a
Gbit NIC, 600 Mbit would be closer.  But right now, for example, my
Gigabit NIC is pushing data at 5.6MB/s -- or roughly 45 Mbit/s.  I just
switched from the 100 Mbit EEPro100 'cause it was going at 8 Mbit/s.
According to dmesg, they're recognized as they should be, and the switch
shows them as having autodetected at the appropriate rate as well.  (Note,
also, that everything's running at full duplex.)  One last data point: it
seems to go reasonably fast -- at least three times faster than it does
later -- during the first couple hundred megabytes.  I'm assuming that
that's cached stuff.  However, the hard drives (I've checked the specs)
should all be able to come close to, or even exceed, gigabit transfer
rates, and the machines aren't busy doing anything else, so I don't think
that drive access should be the bottleneck.

Oh: 2.4.20, Debian.

Any hints/suggestions/etc., would be greatly appreciated.

Thanks,

-Ken


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Re: Network speed degredation?

2003-04-01 Thread Ben Boulanger 
On Tue, 1 Apr 2003, Ken D'Ambrosio wrote:
 Any hints/suggestions/etc., would be greatly appreciated.

Have you tried forcing the switch and network cards to 100/Full?  Auto 
Detection often has issues.

Ben


-- 

Make happy those who are near, and those who are far will come. 

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