[GRASS-user] Grass save on cluster?

[Markus Neteler]

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

> 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.

> 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

Markus