On 1 Feb 2012 at 12:09, Tyler Montbriand wrote:
From: "Tyler Montbriand" <tyler(a)marieval.com>
Date sent: Wed, 1 Feb 2012 12:09:52 -0600
Subject: Re: [Udpcast] using udpcast with 1G ethernet.
What "gigabit" switch did you get? I've
had several lemons. Check
ethtool -S eth0 if you can, if you see lots of RX_PAUSE, your switch
is cheating, spamming pause packets to slow down the traffic to rates
it can handle. It also shows receive errors.
It is a Dell 2724 switch I got off ebay and just downloaded the
manual, so am complete new to it.
I did a test trying to use just two receivers to see if I could get
better results, but was getting about the same results. Then did a
single client test and got speeds of about 290MB with the two
systems doing each separately, but when I tried to do them
together afterwards it was giving like 2MB. I know that single
transfers are unicast, so it seems to be something with the
multicast setup. Have to look into getting in the switches
management to setup the storm settings, but its default IP is not
what this lab is on. Manual says 192.168.2.1
The client which didn't negotiate gigabit on the
first try is strange.
Having to force speed+duplex is one thing, but if the problem GOES
AWAY, that suggests cable trouble to me. I haven't had negotiation
problems that just go away when you try again. Negotiation doesn't
test cable quality, it selects the maximum both support; it should've
picked the maximum speed, first try, unless the cable was so bad
negotiation just plain failed; after which both ends could've picked
the same sane default.
The cables were made by our MIS department long ago, and the
one I replaced had the wires to far out, and the other one I just
recrimped and it then connected. Since I got a 280MB speed on
the two other machines I selected, it doesn't seem to be a cable
issue with those 3 at least.
Also, if you have one slow receiver -- not necessarily a network
problem, a slow disk could do it -- everything will wait for the slow
I have seen this in the past with machines, where one system
would slow down the others, but it generally would just report that
one machine not responding. In this case, the messages always
seem to say that all the machines not responding, so it looks like it
is the switch that is doing something. Even with just two machines
it kept reporting [0,1].
Thanks. Might even try using the broadcast options, and see what
that does. This lab is on its own 192.168.7.x network off a linux
server that has 9 ethernet ports, so it should isolate from rest of
campus, or just disconnect it for tests?
[mailto:email@example.com] On Behalf Of Michael D.
Setzer II Sent: Wednesday, February 01, 2012 6:13 AM To:
udpcast(a)udpcast.linux.lu Subject: [Udpcast] using udpcast with 1G
I just got a 24 port 1GB switch and my first attempt definitely didn't
give the results I was hoping for. Perhaps there are some tuning
options that might improve the options.
First, I created an ntfsclone lzop compressed image of the
Windows partition that is uploaded to one of the machines
connected with the 1GB switch. That took about 11 minutes.
I then made sure that all the machines had the nics running at 1G.
Originally, two machines were only connecting at 100M, but replacing
the connector on 1 and just recrimping the other got them all to
connect at 1G. The cables are all Cat5e, but they are a few years old.
I have a script that using udpcast to transfer this image file to all
the other 19 machines in the lab connected to the machine. I was
hoping to get a better speed when switching to the 100M to the 1G, but
wasn't looking for a 10 times increase, since I knew that the hard
disks only will do about 55MB/ second accordng to hdparm. But in my
first test it took 31 minutes to transfer the file using udpcast??
Image file is about 12GB.
Udpcast mailing list
Michael D. Setzer II - Computer Science Instructor
Guam Community College Computer Center
Guam - Where America's Day Begins
G4L Disk Imaging Project maintainer
Number of Seti Units Returned: 19,471
Processing time: 32 years, 290 days, 12 hours, 58 minutes
(Total Hours: 287,489)
SETI 11801304.490587 | EINSTEIN 7206654.049851
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