Re: Bizarre NFS Problem

["Ben Hutchings" <ben.hutchings@businesswebsoftware.com>]

Derek "The Monkey" Wueppelmann wrote:
> Hello All,
>
> I'm currently running debian 3.0 r3 and have run into an interesting
> issue with my NFS mounts. On one of my debian systems (I have just done
> an apt-get update/upgrade on all my systems) when copying or creating a
> file on one of the NFS mounted directories I get an input/output error.
> The interesting thing is that this only happens for a file size of
> between 4833-4840 inclusive or any multiple of 8192 + 4833-4840. My
> mount point has been setup in fstab with the following options:
>
> rw,auto,soft,rsize=8192,wsize=8192
>
> Another interesting thing is that if I go to another of my debian
> systems that is running the exact same version of mount and nfs the copy
> works just fine. I am incredibly perplexed as to why this is happening,
> if anybody could shed some light on this that would be great.
<snip>

Perhaps it's something to do with IP fragmentation?  That works on 
64-bit (8-byte) units so if there's some kind of bug in fragment 
reassembly somewhere along the route then it might well affect fragments 
in an 8-byte range of sizes.  See if the problem goes away if you reduce 
the sizes to 1024, which should prevent fragmentation.  (This is bad for 
performance so it's not a good solution, but it might help to identify 
the source of the problem.)

Ben.