A Doozer cluster is one or more doozerd processes interconnected with one
another, where all the participants are performing consensus. Each member of a
cluster is referred to as a cal. CAL stands for "Coordinator, Acceptor,
and Learner" as defined by Paxos.
CALs can propose changes to the state of the system (or mutations) through consensus, vote for their proposals and/or others, and learn winning proposals. For more information about this, see [Consensus][].
A doozerd process attached to a cluster that is not participating in
consensus is a slave. Slaves can only learn winning proposals and update their
state accordingly. Meanwhile, they are watching for an available cal
slot to become available. In the event of a cal slot becoming available, slaves
will attempt to lock the right to take over that responsibility.