[p2p-hackers] p2p in some place or other

[Matthew Kaufman]

Greg Bildson:
> There are an infinite number of rare files so caching those 
> without future knowledge about anyone's interest would be 
> costly and infeasible.

On any given actual file sharing network, I believe that's not actually
true. In fact, it "probably" isn't even true for the known universe of
computers :)

The number *can be* very large however, so as has been pointed out before,
how much sense this makes really depends upon the total number of files and
their distribution.

Consider, for instance, the cost of having every file stored on exactly ONE
more node than actually cares about the file at present. If almost all files
are, as we fear, on a very long tail of height one, then this approximately
doubles the storage requirements network-wide (and communiaction required
for that replication scales equivalently). However, that is the
worst-case... Real distributions may not look like this at all, especially
for things like commercial file distribution networks or corporate intranet
applications.

The real trick for the general case is probably selling users on the idea
that the overhead they experience (disk space, bandwidth requirements,
number of times their house is raided in a search for illicit bits) is worth
the performance gains (if any) that they see.

Matthew Kaufman
matthew at matthew.at
www.amicima.com