I am trying to copy a large amount (about 50 GB) of data over my network from a Hyper-V-hosted virtual machine running Ubuntu 11.04 (Natty Narwhal) to another (non-virtual) Ubuntu host that I plan to use for testing upgrades to one of our web applications.
The problem I am having is with
the virtual machine, which I shall refer to in what follows as "source.host". This machine is running 64-bit Ubuntu Server with
the 2.6.38-8-server kernel and
the Microsoft Linux Integration Components for Hyper-V kernel modules (hv_utils, hv_timesource, hv_netvsc, hv_blkvsc, hv_storvsc, and hv_vmbus) loaded. It uses a Hyper-V "synthetic network adapter" for its networking interface.
To do
the copy, I log on to
the machine with
the data and run
the following commands (Call
the remote machine "destination.host".):
$ cd /path/to/data
$ tar -cvf - datafolder/ | ssh
[email protected] "cat > ~/data.tar"
This runs for a while and then suddenly stops after transferring somewhere from 2-6 GB.
The terminal on
the source.host machine displays a Write failed: broken pipe error.
The odd part is this: after this occurs,
the "source.host" machine is no longer able to talk to
the rest of
the network. I cannot ping any other hosts on
the network from
the "source.host" machine, and I cannot ping
the "source.host" machine from any other host on
the network. I am equally unable to access
the any of
the web services hosted on "source.host".
Running ifconfig on "source.host" shows
the network adapter to be up and running as usual with
the correct IP address and everything. I tried restarting
the networking service with
$ /etc/init.d/networking restart
but
the problem does not go away. Restarting
the machine makes it capable of talking to
the network again -- it can ping and be pinged by other hosts, and
the web services are also accessible and usable as normal -- but attempting
the copy operation again results in
the same failure, requiring another restart.
As an experiment, I tried replacing
the tar -- ssh pipeline above with a straight scp:
$ scp -r datafolder/
[email protected]:~
but to no avail
Thinking that
the issue might have to do with
the kernel packet-send buffers filling up, I tried increasing
the buffer size to 12 MB (up from
the 128 KB default) with
# echo 12582911 > /proc/sys/net/core/wmem_max
but this also had no effect.
I'm guessing at this point that it might be a problem with
the Microsoft synthetic network driver, but I don't really know. Does anyone have any suggestions?
Thank you very much in advance!
