[Udpcast] Lots of Timeouts using udpcast

Michael D. Setzer II mikes at kuentos.guam.net
Mon Feb 27 05:12:13 CET 2006

Hash: SHA1

On 26 Feb 2006 at 19:26, Benjamin Moore wrote:

Date sent:      	Sun, 26 Feb 2006 19:26:47 -0800
From:           	Benjamin Moore <bmoore at tacticallanguage.com>
To:             	udpcast at udpcast.linux.lu
Subject:        	[Udpcast] Lots of Timeouts using udpcast

> Hello,
> I've just recently(as in the last hour) started playing with udpcast to image a
> bunch of Windows XP machines.
> I seem to have gotten everything working, but the throughput is kind of slow
> because of the large number of time out errors I am getting.
> This is the error:
> Timeout notAnswered=[0,1] notReady=[0,1] nrAns=0 nrRead=0 nrPart=2 avg=<now
> hovering around 59k>

Some questions about the setup. Is it one or two machines that is giving the 
timeouts? I have a lab of 20 machines, one was causing this problem. If I 
imaged all the others together there would be very few timeouts compared 
to thiis one. Turned out to be the hard drive in that machine, which was the 
same brand as all the others. In swapping the hard drive to another machine 
the problem moved from the one machien to the other. Ran diagnostics on 
the drive,and it reports no errors, but it doesn't seem to be able to keep up 
with writing the sections of the drive that are blank, so the compressed 
informaiton is coming in faster than the machine can write it to the disk. I've 
seen that these drives can only do about 45MB after the buffer gets full.

Also, what IP addresses are you using on the systems. I had a problem, 
whereas the College MIS has 3 Class C blocks all the the same physical 
network with a standard Class C subnet mask (Don't ask why??), and if I 
used dhcp it would only work with machines on the same class C. I ended 
up making an ipmac.txt file for the udpcast, and had it assign 10.0.7.x 
numbers to my machines (Lab D-7). 

Also, you could try a cross-over cable and directly connect two machines, 
and see if it differs from going thru the switch..

Another issue that you might want to look at, are you clearing the unused 
space on the drive before doing the transfer. I have a program that I use with 
my G4L project (at least the last four releases) and udpcast. 
Is a little C program (source code at the same site with .cpp), and it works 
for FAT and NTFS partitions. I just copy the file to the machine, and from the 
command prompt you blank6 c  (c being the drive to clear). It just creates 
2GB files full of nulls until the disk is full, and deletes them when done. This 
will speed up the compress and greatly reduce the time to transmitt the data. 
When I image my lab machines, I can get about 20+ MB/sec considering the 
uncompressed size of the 80GB drives. 

Don't know if that help, or just confused things more. Just yesterday, I 
imaged the other 19 machines in my lab with 80GB drive in about 50 
minutes with a hub.

One other thing that you might want to look at is the --max-bitrate= option.
I've found that if I set it to 90M it reduces these timeouts for the 18 
machines, and 80M will sometimes have none. With the problem machine, it 
usually takes 60M or lower to stop the errors. 

> Periodically udpcast seems to recover and the throughput goes back up.  But then
> it starts getting Timeouts again.
> THe configuration right now is 2 machines recieving and the machine transmitting
> all plugged into the same switch.  I will be doing a second run with 20 machines
> tomorrow.
> It looks like everything is working otherwise, so I'm just curious what's going
> on.
> Thanks,
> Ben
> _______________________________________________
> Udpcast mailing list
> Udpcast at udpcast.linux.lu
> https://lll.lgl.lu/mailman/listinfo/udpcast

  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                        

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