[OpenAFS] afs stalled for large files, opeanfs 1.6.1, ubuntu 12.04, particular network

Jeffrey Hutzelman jhutz@cmu.edu
Fri, 18 Apr 2014 18:11:59 -0400

On Sun, 2014-04-13 at 18:19 +0200, Liza M wrote:
> Hello, 
> I am having a rather interesting problem with opeanfs 1.6.1, ubuntu 12.04 : 
> on one particular network I do not seem to be able to work with files with size ~> 1.4 kB  . 

> When trying to e.g. copy or open larger files, the afs process stalls
> and I am not even able to kill -9 it.  
> On the other hand, the same operation (copy or open large files with
> the same client and host machines) performed on other networks works
> fine. 
> I need to work on afs on particular network on which it is stalling,
> but have no good ideas on how to proceed. Do you have any ideas on how
> to debug and/or get afs to work on the network on which it is getting
> stalled? I pass details on my setup and fstrace logs below.

This sounds like an MTU problem -- your connection to the network in
question includes a segment with a lower MTU than those to which the
fileserver and client are directly connected.  Perhaps there is a VPN or
other tunnel in between?

Try running this command (as root) on the client:

ip link set dev eth0 mtu 1200

Replace "eth0" with the name of the relevant interface.

If this makes the problem go away, you know that the problem is that
some portion of the network is not passing packets above the configured

-- Jeff