[Radiance-general] NFS and rpiece

[Jack de Valpine]

Hi Francesco,



Francesco Anselmo wrote:
> Hi Jack,
>
> Thanks for your extremely useful input on this topic.
>
>   
Well let's reserve judgment and see how things work out... ;->
>> 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.
>>     
>
> Thanks for pointing me to this URL, I should have checked it before.
> Effectively it is the single most useful resource about NFS on linux :)
> so much better than the man pages.
>
>   
Yes, but I am not sure that it make it that much easier to figure out 
how to do what we need to do.
>> 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).
>>     
>
> I will ask to change the configuration next Monday, and hopefully
> things should improve.
>
>   
>> 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.
>>     
>
> Yes, I'll keep you updated on my trials&errors.
>
> I have been using OpenMosix with oMFS so far, and it has been working
> properly, especially after the DFSA has been introduced.
> (for more info about oMFS and DFSA there is a short section in
> http://howto.x-tend.be/openMosixWiki/index.php/FAQ)
>
> I understand that the OpenMosix development is moving towards using
> GFS (Global File System) now:
> http://www.redhat.com/whitepapers/rha/gfs/GFS_INS0032US.pdf
>
>   
I have experimented with OpenMosix (3 or 4 years ago it seems). I have 
had some reasonable success with another  cluster system called OpenSSi 
(www.openssi.org), which has a cluster wide filesystem called cfs. I am 
currently looking at something called warewulf (www.warewulf.org) and 
thinking about running diskless clients. I have had some discussions 
with the people on the list there and some of the things that have been 
suggested are: lustre (www.lustre.org) and pvfs2 (www.pvfs.org). These 
are cluster oriented distributed filesystems, though I do not no how 
they manage file locking and cache coherence across all nodes. People on 
this group have also suggested that NFS might be ok on a small cluster 
assuming a well configured server.

When you are using OpenMosix and Radiance are you letting OpenMosix 
migrate automatically or are you specify which node you want a given job 
to run on. Do you find it distributes rpiece jobs correctly?

> Thanks again, and have a nice week-end.
>
> Francesco
>
>
>
>
>
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>
>   

-- 
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
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