[Udpcast] Speed dropping down
Michael D. Setzer II
mikes at kuentos.guam.net
Fri Mar 25 22:17:16 CET 2005
Not sure if this applies to your situation, but this is what I
have done in recent work to add udpcast as an option with
I use G4L to create a image file on my server using lzop
I can then use
udp-sender --file image --max-bitrate 80m
What I originally tried on the clients didn't work, and I got a
reply that worked perfectly.
Why don't you simply use
udp-receiver --pipe 'lzop -d -c -' -f /dev/hda ?
I've also used the latest options to build boot diskettes that I created
with the mac table to assign ip addresses to each machine, and just
ran the model machine with sender mode with only the --max-bitrate
80m option to 19 machines. Setup the diskettes with default lzop
compression. Took about 50 minutes to image to 19 machines with
80 gb drives.
One last issue that I found in making images, is that clearing out
unused sectors makes a big difference. I did an image of a clean
install of linux on a drive, and it created a 12GB file. I then blanked
out the unused sectors, and got a 2.5GB file.
dd if=/dev/zero of=/0bits
I've never used the PXE, so don't know if this doesn't apply, but it is
things that I found that make the udpcast work great for me.
Again, a geat program.
On 25 Mar 2005 at 18:02, Lukas Kolbe wrote:
From: Lukas Kolbe <lucky at knup.de>
To: udpcast at udpcast.linux.lu
Date sent: Fri, 25 Mar 2005 18:02:11 +0100
Subject: [Udpcast] Speed dropping down
> First of all, thanks for this extremely useful tool.
> We use it to copy hd-images to a pool of 48 PCs, and it works
> surprisingly well. At least, last semester it did :).
> We use PXE to boot all clients into a small debian-system with r/o
> nfs-roots, and cluster-ssh to control them all at once (eg., start
> udp-receiver). Network is 100mbit half-duplex, the switch can
> 102gbit internally. Unfortunately, we have no physical access to
> On the server, we use this command to cast the complete
> cat /dev/hda | lzop -c - | udp-sender --half-duplex --max-bitrate
> On the clients, the opposite is:
> udp-receiver | lzop -d - | dd of=/dev/hda
> hda has about 29gb of used data, and a capacity of 80Gb. We do
> clients at the same time, and the first round went very well (it took
> about 105 minutes to write the whole disk).
> Now, the problem for the second 16 (which are the same
hardware than the
> first 16) is, that the speed of udpcast has dropped down from
> 50mbit/s (with which it transferred about 24Gb) to right now about
> 50kbit/s (with which it has transferred about 5gb yet) (that's ok for
> now, as they can finish writing the image over the easter-
> many timeoutnotanswered-messages on the sender.
> These messages came from all clients every few seconds when
> was about 50mbit/s, but the client number 2 was overrepresented
> and the speed dropped down to about 50kbit/s, so I cut it off.
> When udpcast reduces the speed to that of the slowest receiver,
> receiver gets cut off, would it be possible that the speed gets up
> again? At the moment it doesn't seem so ...
> Thanks in advance, Lukas
> Udpcast mailing list
> Udpcast at udpcast.linux.lu
Michael D. Setzer II - Computer Science Instructor
Guam Community College Computer Center
mailto:mikes at kuentos.guam.net
mailto:msetzerii at gmail.com
Guam - Where America's Day Begins
Number of Seti Units Returned: 15,966
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