[Wien] Configuring SCRATCH variable for parallel computation

[Michael Sluydts]

Hello César,

To perform parallel calculations you do need a shared directory between 
all nodes. As you have described '/home' appears to be a form of shared 
storage.

What its intention is, is of course not well-known to us. If it is 
shared there is no direct reason it cannot function for wien, however 
the problems that might occur are:
-the connection to the shared storage is too slow - if it is not meant 
to transfer files from and to during a calculation
-there is not enough space - if it is just meant for temporary storage 
and user settings
-the /home is meant as a login system and not for actual user usage

Maybe contact the person who set up this cluster and ask them what they 
recommend.


Regards,

Michael Sluydts

César de la Fuente schreef op 13/02/2014 17:09:
> Hi,
>
> I 'm doing some tests in the Memento cluster of the University of Zaragoza
> on TiC system with a k- 100k pts , 4 nodes with 64 CPUs per node. It is a
> system that does not share RAM and hard disks between nodes during
> calculations. Initially the parallel computation with Wien2k stopped in the
> first cycle because a file system problem. The variable $ SCRATCH point to
> the local hard disks of each node used in the parallel computation.
> Fortunately I was able to finish the calculation re-directing the variable $
> SCRATCH to /home directory that it is shared by all nodes. The calculation
> finish fine and it is correct, but I think that something is wrong. Wien2k
> not seems  to be originally designed for a parallel calculation using /home
> as SCARTCH.
>
> Is it correct to use the /home directory as SCRATCH in Wien2k ? , Can this
> cause problems in the OS of Memento's cluster or in  future wien2k
> calculations?. In fact, I'm having other problems with wien2k in other
> systems but I'm not sure if it is because SCRATCH points to /home directory
> or not.
>
> Thank you for your attention and appreciate any comment.
>
> Sincerely,
>
> Dr. César de la Fuente.
> Depto. de Física de la Materia Condensada.
> Edificio Torres-Quevedo
> EINA-Universidad de Zaragoza.
> C/María de Luna 3, 50018-Zaragoza (SPAIN).
>
>
>
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