[GRASS-user] Grass save on cluster?

[Rainer M Krug]

On Sat, Mar 21, 2009 at 4:31 PM, Markus Neteler <neteler at osgeo.org> wrote:
> On Thu, Mar 19, 2009 at 2:14 PM, Rainer M Krug <r.m.krug at gmail.com> wrote:
>> Hi
>>
>> how save is GRASS 6.3.2 to be used on a cluster? I am starting several
>> instances of grass on a single node, they all have their own grass
>> database (but they share a linked PERMANENT and the name of the mapset
>> and location is the same). I am asking as I experience from time to
>> time crashes in my simulation because certain files can not be found,
>> and these crashes are not reproducible when only one GRASS instance
>> runs.
>
> I cannot say for 6.2.3, but I have run > 100k jobs in parallel with 6.4.0x,
> also having the sharing nodes (using PBs and lately only Grid Engine).

Are these in different mapsets? I am asking because we might be using
grass as a backend for a web-application - and when it can handle that
many parallel jobs, it should work.

> Certain files can not be found didn't happen at all.
> Which are these files?

I am running a simulation, and these are layers which should have been
created before.

>
>> In addition, how safe is it to execute several r.mapcalc and other map
>> operations in the same mapset in parallel (obviously with different
>> maps)?
>
> You can do that unless the current region isn't touched. But it is
> not really recommended.

I am definitely not changing the region, so the error must be somewhere else.

>
>> Again, I experienced severe problems with that, wherefore I
>> abandoned it (although it increases my simulation time considerable).
>> I would have expected it to work, but again, I had non reproducible
>> (and inconsistent) crashes.
>>
>> Can somebody comment on that or provide some pointers?
>
> Sure:
> http://grass.osgeo.org/wiki/Parallel_GRASS_jobs

Thanks - this looks very intersting - I'll look into it.


Thanks

Rainer


>
> Markus
>



-- 
Rainer M. Krug, Centre of Excellence for Invasion Biology,
Stellenbosch University, South Africa