Ryan Sweet rsweet at aoes.com
Thu Mar 3 00:29:56 PST 2005

On Tue, 1 Mar 2005, Rajiv wrote:

> Dear All,
>   I have setup Globus 3.2 on two machines and I am able to submit job from
> one machine to another. I have a basic doubt about what application to run
> in GRID environments. Shouldn't the GRID application use resources of both
> the GRID machines simultaniously. Are there any applications like this. So
> far I am only running remote jobs from on machine to another - for eg I can 
> submit
> and run LINPACK/GROMACS job from one master of a cluster to a master of
> another cluster.

Dear Rajiv,

There seem to be a lot of people building clusters and grid systems lately 
without applications to run on them ;-).  That's nice to see, I guess, in as 
much as it indicates the broad level of acceptance for the technologies.  It 
is very much the reverse of the "to scratch an itch" way in which things used 
to be done. ;-)

Grid systems (the term means many things to many people - here I mean roughly 
"a collection of resources used in collaboration spanning multiple 
geographic locations and administrative domains") are used in a wide variety 
of ways.  In your scenario, if you are building a globus system in order to 
learn about globus, and you can now run jobs on one host from another and 
vice-versa, you've already got a lot of the hard work done.

If you would like to use multiple grid resources to simultaneously work on a 
larger problem than any of them can tackle when working alone, then you need a 
way to take your problem and partition it into chunks that can be submitted to 
various resources around the grid, in your example, split a larger problem in 
two, and submit half to each resource.  It is not usually practical (though 
there are exceptions) to run jobs which have a parallel communication 
component (MPI or PVM) across grid resoures (submitting multiple local mpi 
jobs to multiple resources is ok though, provided that you have a way to 
verify that the resources can accept your mpi jobs and run them - thats where 
RSL and a broker, etc. come in). Some middleware to broker between the 
requirements of your job and the available resources is usually used.  There 
are a lot of projects that do that, and any attempt I would make to list them 
would surely leave out one or more deserving ones.  Google is your friend.

For GROMACS there are lots of examples out there.  Here is a very friendly 
one from the UK NGS: http://www.ngs.ac.uk/sites/ox/software/gromacs.html


Ryan Sweet             <ryan.sweet at aoes.com>
Advanced Operations and Engineering Services
AOES Group BV            http://www.aoes.com
Phone +31(0)71 5795521  Fax +31(0)71572 1277

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