Uses for a beowulf cluster?

[Kragen]

On Mon, 14 Sep 1998, Daniel J. Frasnelli wrote:
> 	He went on to say that multicasting node activity/status would
> diminish the effectiveness of the network, and suggested a round-robin DNS
> configuration.  

Suppose your machines are networked in a ring topology with 9600bps
serial lines, and they report their status every 30 seconds.  Suppose
the status report is a UDP datagram containing the node's name (say,
ten bytes) and its current load average (say, five bytes).  The IP
header is 20 bytes, the UDP header is 8 bytes, and the payload is
another 15 bytes.  If you're using SLIP, you have another byte for
framing, for a total of 44 bytes per status report.

If you have 32 machines, you'll broadcast 32 * 44 = 1408 bytes, which
becomes 14080 bits with normal serial settings, every 30 seconds.
That's about 1.5 seconds out of every 30 seconds taken up by status
messages, or about 5%.  You could include an extra 44 bytes of stuff in
your status messages to bring it up to 10%.

If a bigger network than you plan, on an absurdly slow physical data
link, would be 5% loaded by a straightforward implementation of
broadcasting node activity and status, I think you won't have a
problem with network loading due to multicasting node status.

Kragen

-- 
<kragen@pobox.com>       Kragen Sitaker     <http://www.pobox.com/~kragen/>
The sages do not believe that making no mistakes is a blessing. They believe, 
rather, that the great virtue of man lies in his ability to correct his 
mistakes and continually make a new man of himself.  -- Wang Yang-Ming