I asked my wife Amber for help formalizing my intuition about what sort of share placement makes me happy. We came up with this:
First of all, let's call a set of servers "sufficient" if you can download the file from that set (i.e. if at least K distinct shares are hosted in that set of servers). Now consider the largest set of servers such that every K-sized subset of it is sufficient. Let's call the size of that largest set S. Now my intuition about "Happyness" is that I configure a Happyness number H, and if an upload results in an S >= H then I'm happy. I think this is also Robert Metcalf's intuition [1]. It may also be Shawn Willden's intuition [2], but on the other hand perhaps Shawn Willden's intuition is something more sophisticated. ;-) A neat thing about this way of thinking is that the number S is the "health" or "robustness" of the file. An upload or a file-check operation could report S to the user. What do you think -- is this measure of "health" a good enough measure for the purposes of ticket #778? Regards, Zooko [1] http://allmydata.org/pipermail/tahoe-dev/2009-August/002494.html [2] http://allmydata.org/pipermail/tahoe-dev/2009-October/002972.html http://allmydata.org/trac/tahoe/ticket/778 # "shares of happiness" is the wrong measure; "servers of happiness" is better _______________________________________________ tahoe-dev mailing list [email protected] http://allmydata.org/cgi-bin/mailman/listinfo/tahoe-dev
