[Udpcast] Speed dropping down

Lukas Kolbe lucky at knup.de
Fri Mar 25 23:09:51 CET 2005

Am Samstag, den 26.03.2005, 07:17 +1000 schrieb Michael D. Setzer II:
> 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 

When I use a max-bitrate higher than 70m, I get lots of Timeout
notAnswered messages. With 70m it seems to work just fine.

> 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 ? 

Yep, that's how i tried it the last time. It seems to have worked (it
transfered 25GB in about 1 1/2 hrs), but this was with only 4 receivers.
I hope that I will be able to test this configuration again with 16 or
even 32 receivers, albeit then I wont't be able to cast the whole
harddisk (for the obvious reasons that we need to reactivate Windows on
every machine with a norton ghost walk-disk), just the linux-partition
(which works perfectly out of the box on all clients).

> 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 

Yep too, I dit this before the last run, and it reduced the overall size
from 29Gb to 25Gb (where about 17GB is the windows-partition).

> 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. 

PXE is just awesome to use - just tell your dhcp-server which client
shall boot the netboot system, restart them, and du a "cssh
root at host{0,1}{0..9}".

I'll possibly look into G4l, but I am not yet convinced that the
copryright-infringement issues are solved.


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