disadvantages of linux cluster (Stephane Glockner)

[Manel Soria]

> I work in a french university laboratory. We do massive Computational
> Fluid Dynamics at present time on ORIGIN2000, IBM Regatta... The solution of
> a Beowulf cluster seems very interesting as regards as financial cost and
> performances.
> We would like to use it in the following manner :
> - multi users (around 10 or 15 users)
> - multi single-processor, light and heavy applications (<=2Go of RAM)
> - use of a parallel version of our application

Here is our experience in case it is useful for you:

We have a simular environment: university,CFD, about 10 users, multi single processor
applications, parallel simulations with up to 10 processors and a DNS code for
incompressible flows that runs quite well with up to 36 processors. All the CFD codes have
been developped by us. The parallel codes use MPI.

In general we are happy with our 74 processors 100-Mbit/s cluster (Debian). We cannot
compare with SGI becouse we never had such an expensive system. However, before
buying the cluster we used to access large SGI  and IBM/SP2 machines (central resources
of the university).  The main difference is that the cluster processors are cheaper and we
can have VERY long run times and nobody complains.

As for the disadvantadges:  The low reliability of the hardware, more administration
problems, the space used by the machines and the need of a new cooling system.

Also, the development of the required parallel CFD codes and algorithms
tolerant to slow networks was (and still is) hard ... but we are writting papers about
that ... afterall this is suposed to be out job :-)

In summary, I would recommend you to go for the Beowulf cluster. Maybe begin with a
small system and let it grow, as we are doing.


--
===============================================
Dr. Manel Soria
ETSEIT - Centre Tecnologic de Transferencia de Calor
C/ Colom 11  08222 Terrassa (Barcelona) SPAIN
Tf:  +34 93 739 8287 ; Fax: +34 93 739 8101
E-Mail: manel at labtie.mmt.upc.es