What is a Cluster?

[Greg Lindahl <lindahl@conservativecomputer.com>]

By the way, one thing that needs to get defined is the definition of
"Cluster". I recommend that you all run (not walk) to buy Greg
Pfister's book "In Search Of Clusters" and read it. He defines 3
classes:

1) High Availability Clusters
2) High Performance Clusters (run a single program fast)
3) High Throughput Clusters (run a zillion non-parallel programs)

An example of (1) is a 2-node failover mail server.
An example of (2) is a Beowulf running a single big mpi job.
An example of (3) is a Beowulf running a bunch of single-cpu gene
  comparison jobs.

Some clusters are combinations of these. Most webserver front-ends are
a combination of (3) and (1): you distribute the load of hits over
many nodes, and if one goes down, you don't send it new hits.

I think these definitions help give a good idea of the scope that
cluster services can serve. It's often the case that the community
that works on (1) never talks to the community that does (2) or
(3). And people doing (2) and (3) for enterprise apps often don't talk
to the people doing (2) or (3) for technical computing. It would be
nice if this list turned into a forum where various groups could meet
and figure out how we can help each other.

-- greg


Linux-cluster: generic cluster infrastructure for Linux
Archive:       http://mail.nl.linux.org/linux-cluster/