[Udpcast] Image does not complete correctly (receiver hangs)

D Teed dteed at artistic.ca
Tue Jan 3 21:25:05 CET 2006


Hi,

I could be wrong, but the problem may be that you just have to wait.

Is the hard drive on the target machine still active (LED on)
when it apparently hangs?  If so it might still be working fine.

In our environment, the last part of the write is an empty part
of the disk, which is highly compressed.  Our 512 MB RAM notebooks can
hold a lot of compressed and zeroed data in memory, and it
works out to about 5 GB of data to be written to disk.  For us,
it is normal for there to be a delay of between 5 and 10 minutes
between the disconnect and the completion of writing to disk.
If one used a slower disk on the target, and had lots of memory,
this could even be more extreme difference between disconnect
time and completing the write to disk time.

If network card X and Y are on different target client machines,
then it might have nothing to do with the network cards.

If the same machine is involved with these 2 network cards, then
it might be a hardware or driver issue.

--Donald Teed


On Tue, 3 Jan 2006, Ramon Bastiaans wrote:

> Hi all,
>
> I have been using udpcast to image machines succesfully for a while now.
> Now we are expanding our infrastructure with more machines and extra
> networks, which I would like to image with the same server.
>
> This seems to work a little, except for the fact that it does not
> complete correctly on the new network(card/interface).
>
> The receiver seems to get allmost all data, but the udp-receiver seems
> to 'hang' at the end.
> The most frustrating part is the udp-sender that says "Transfer
> complete, disconnecting".
>
> When I try it in unicast and sniff the network I see the following on a
> _succesfull_ image to networkcard X:
> 16:06:59.620836 IP 192.168.16.3.9033 > 192.168.17.140.9032: UDP, length:
> 1472
> 16:06:59.620841 IP 192.168.16.3.9033 > 192.168.17.140.9032: UDP, length:
> 1472
> 16:06:59.620846 IP 192.168.16.3.9033 > 192.168.17.140.9032: UDP, length:
> 1472
> 16:06:59.620851 IP 192.168.16.3.9033 > 192.168.17.140.9032: UDP, length:
> 1472
> 16:06:59.620856 IP 192.168.16.3.9033 > 192.168.17.140.9032: UDP, length: 144
> 16:06:59.621146 IP 192.168.17.140.9032 > 192.168.16.3.9033: UDP, length: 8
> 16:06:59.621198 IP 192.168.16.3.9033 > 192.168.17.140.9032: UDP, length: 144
> 16:06:59.621397 IP 192.168.17.140.9032 > 192.168.16.3.9033: UDP, length: 8
> 16:07:00.654842 IP 192.168.16.3.9033 > 192.168.19.255.9032: UDP, length: 28
> 16:07:01.146772 IP 192.168.17.140.9032 > 192.168.16.3.9033: UDP, length: 4
>
> When I do the same (failing) image to networkcard Y:
> 15:27:13.413078 IP 192.168.144.2.9047 > 192.168.144.200.9046: UDP,
> length: 1472
> 15:27:13.413084 IP 192.168.144.2.9047 > 192.168.144.200.9046: UDP,
> length: 1472
> 15:27:13.413089 IP 192.168.144.2.9047 > 192.168.144.200.9046: UDP,
> length: 1472
> 15:27:13.413095 IP 192.168.144.2.9047 > 192.168.144.200.9046: UDP,
> length: 1472
> 15:27:13.481157 IP 192.168.144.2.9047 > 192.168.144.200.9046: UDP,
> length: 144
>
> And then nothing.
> This is the last part of the imaging process, right up till it completes
> at networkcard X, and just hangs on networkcard Y.
>
> It seems to me the last few packets are missing and that's causing the hang.
>
> Anyone experienced something like this before and/or has any pointers to
> what might cause this?
> I suspect a switch or similar device to block the last packets. I.e. a
> rate limiting setting or something.
>
> Kind regards,
> - Ramon Bastiaans.
>
> --
> There are really only three types of people:
>
>   Those who make things happen,
>    those who watch things happen,
>    and those who say, "What happened?"
>
> ---
> ing. R. Bastiaans
> HPC  - Systems Programmer
>
> SARA - Computing and Networking Services
> Kruislaan 415      PO Box 194613
> 1098 SJ Amsterdam  1090 GP Amsterdam
>
> _______________________________________________
> Udpcast mailing list
> Udpcast at udpcast.linux.lu
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>



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