Re: available resource declaration language(s)

[Alan Robertson <alanr@unix.sh>]

David Santo Orcero wrote:
> 
>  Hello, all!


> 3) If the network is really BIG -500, 600 nodes- the delay to get the
> token will be a problem. Somebody can say -buy a faster network-; but it
> is better not to force to the user spend more bucks because we use a worse
> solution.
> 
>  The three problems can be solved in a broadcast net, as proposed? No! If
> you have enougth nodes, you will flood the network; that is why I am
> really sure that using broadcast features it will not work.

This is a common misconception.  I've done the calculations on this, and
they don't support your assertion.  See the heartbeat design paper
referenced earlier:
	http://linux-ha.org/comm/HBdesign.pdf

Paraphrasing from that paper:
For a 1000 node system and a 150 byte heartbeat packet, and a 1 second
heartbeat interval, the bandwidth is approximately 1.2% of the bandwidth
available on an unswitched 100 Mbit network.

If you double the packet size, it would rise to 2.5%.  This is pretty small
for such a large cluster.  I would hope that such a large cluster would have
faster networking anyway ;-)

	-- Alan Robertson
	   alanr@unix.sh

Linux-cluster: generic cluster infrastructure for Linux
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