[Beowulf] What's the category of Beowulf among Clusters?

Mark Hahn hahn at mcmaster.ca
Fri Dec 19 09:07:23 PST 2008

>     Clusters, Grids, MPPs, MPI, OpenMP, HA, LB, GPGPU, FPGA, SMP, NUMA,
> SSE etc..
>     These abbreviations and terms almost cram my head, so I have to
> redvelop and re-index them in my memory(brain).

think of what the acronym is abbreviating, and the logic of that name.

>     As a newbie, when I read the articles in wikipekia, I got confused.
>     In the segment Cluster categorizations
> <http://en.wikipedia.org/wiki/Computer_cluster#Cluster_categorizations>

that's horrible and incomplete.

IMO, HA and load-balancing are not really distinctly different, since 
LB is really just active-active HA.  (or HA is active-passive LB).
other than HA/LB, clusters are computational.  within compute clusters,
the main distinction is how tightly coupled they (or the programs they run)
are.  grids are the extreme loose end: basically no inter-node communication,
often geographically distributed, often ad-hoc collections of different kinds
of machines run by different organizations.  the opposite is a homogenous,
tightly-coupled cluster with a dedicated local network optimized for
inter-node communication and running few multi-node jobs.

> , both "Cluster computing" and "Grid computing" are the subclasses of

"cluster computing" is descriptive: the entity is a set of nodes somehow
combined, usually by a local communication fabric.  by definition, the nodes
are separate, so distributed.  (the 'distributed' here means that
communication is by explicit message passing; the opposite is shared-memory,
where communication is implicit and done by read/write operations to memory.)

"grid" is a marketing term for "loosely coupled distributed clustering";
it was a trendy word 10 years ago, but has fallen into disuse because it's 
so generic (and not all that widely applicable).

> "Distribute computing" ,and the third one is "Massive parallel
> processing ". IMHO, the latter category is more reasonable(right or not?) .

MPP doesn't mean much; its best to avoid the term and stick to more 
specific ones.

>     However, since there are too many cluster software products, how
> can I categorize Beowulf like clusters( loosely coupled, use MPI)? or

beowulf certainly does not imply loose coupling (or rule out PVM.)

> what's the category of Beowulf like clusters?

beowulf is compute clustering using mostly commodity hardware and mostly 
open-source software.

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