[Beowulf] Small Distributed Clusters

[Ian Pascoe]

Hi all,

Firstly before getting into the nitty gritty of my question, a bit of
background.

Myself and a friend are looking to set up initially two small clusters of 4
boxes each, using old surplus commodity hardware.  The main purpose of the
cluster is to hold data and perform calculations upon it - the data coming
in from external sources.

So far we've decided on a Ubuntu Server base with NFS linking the nodes
together, and we're looking currently at how to perform the calculations -
ie write our own software or adapt existing.

However, the question I have relates to linking the two clusters together.
For the majority of the time, they will be run automonously, but on
occasions we believe they'll need to be run as a cohesive unit with jobs
being passed between them, because we don't plan to duplicate the data
across the clusters, but back up locally.

Both will be connected to the Internet using ADSL and the limitation will be
the upload speed of a maximum of 512Kbs.

How would people suggest linking the two clusters together using a secure
connection?  Performance at this point is not in the equation, just the
ability to securely connect.

BTW Any thoughts too on a SQL Server that would cope well in this scenario?

Thanks

Ian