25 Mar
2005
25 Mar
'05
9:17 p.m.
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
G4L.
I use G4L to create a image file on my server using lzop
compression.
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
rm /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(a)knup.de>
To: udpcast(a)udpcast.linux.lu
Date sent: Fri, 25 Mar 2005 18:02:11 +0100
Subject: [Udpcast] Speed dropping down
Hello!
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
handle
102gbit internally. Unfortunately, we have no physical
access to
the
switch.
On the server, we use this command to cast the complete
harddisk:
cat /dev/hda | lzop -c - | udp-sender --half-duplex
--max-bitrate
90m
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
about 16
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
about
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-
weekend), with
many timeoutnotanswered-messages on the sender.
These messages came from all clients every few seconds when
the speed
was about 50mbit/s, but the client number 2 was
overrepresented
there
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,
and that
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
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