Upstream likes to move "old" releases to an archive mirror as soon as a
new one is released. This is now handled for free by mirrors.nix.
(No idea why cs.utah.edu was used to begin with; it's now added to
mirrors.nix. Note that it doesn't support SSL, but that applies to
several others so I don't see the harm.)
${cassandra}/conf/cassandra-env.sh calls free program on Linux systems in
calculate_heap_sizes().
Adding procps to the path makes the free program available.
According to the project website (http://cassandra.apache.org)
version 2.0 is the most stable version. It's the one that's
recommended if you are already in production or going into
production soon.
Cassandra 2.0 is also the version that's officially supported
by Titan (http://thinkaurelius.github.io/titan), a distributed
graph database that uses cassandra as one of it's backends.
