[Radiance-general] NFS and rpiece

[Jack de Valpine]

Hi Francesco,

> Details of the Redhat 9 NFS system are here:
> http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/ref-guide/ch-nfs.html
>
> NFSv3 is the default, so I guess it is the one used (I'm not the
> administrator of the cluster), but it is also possible to use NFSv2.
>   
I am quite sure that you must use NFSv3.
> I need to check what's in the /etc/exports file, now that I think about
> it. Changing sync/async and wdelay/no_wdelay could have some effect.
>   
I have struggled with NFS based file locking (on Linux) on and off for 
quite some time. Most of our work usually uses smp nodes so this is 
normally not an issue.
But I have been looking back into this more recently for some cluster 
based rendering. I would seriously suggest taking a look at:

    http://nfs.sourceforge.net/

Which has a fairly extensive set of information on NFS.

For locking to work correctly I am pretty sure that you need to specify 
the (sync) option on the server and/or the client side. However NFSv3 is 
supposed to do sync by default as apposed to v2 which did aysnc. The 
latter is faster however leads to a wide variety of issues. It is quite 
likely that you also need to specify the (noac) option, which means that 
the client is not caching file status information instead it always goes 
to the server to check the file status. Both of these options together 
make things slow... To improve performance I believe that you can do a 
couple of things: 1) increase number of nfsd processes available to 
handle requests and 2) specify larger rsize and wsize (assuming a fast 
network transport).
> >From the client side, initially the options were 
> rw,soft,bg
> I think now they are more like  
> rsize=8192, wsize=8192, auto, user, rw
>
>   
I read somewhere, that (hard,intr) is preferable but I will have to look 
this up.

Please note that I have been trying to read up on this as well as other 
shared filesystems, I have not had a chance to test a lot of this out. I 
would be interested to hear what you learn.

-Jack
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