PlanetLab is a cool idea – a bunch of interested parties contribute machines to a planet-wide network, allowing them all to request a slice and perform larger-scale experiments than they would otherwise be able to do. One problem that I've noticed as we have tried to experiment with a slice is that there are really no guarantees of availability – our slice was assigned up to a little over a thousand nodes, and we selected a subset of somewhere around 130 nodes. While testing our experiment scripts, we found that a number of those nodes, while reported available and working, did not respond to our SSH requests. Kind of a pain – we want to hit an exact number for this experiment, so knowing which nodes we can rely on seems pretty critical. I would love to have more information on a history of reliability of nodes on PlanetLab rather than the current “responding” sort of status indicator they show. Maybe they do it already, but I haven't seen it, and if not, it doesn't seem like keeping a history of statuses should be too difficult.
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