Implementing Replica Set Priorities, Kristina Chodorow explains replica sets:
Replica set priorities will, very shortly, be allowed to vary between 0.0 and 100.0. The member with the highest priority that can reach a majority of the set will be elected master. (The change is done and works, but is being held up by 1.8.0… look for it after that release.) Implementing priorities was kind of an interesting problem, so I thought people might be interested in how it works. Following in the grand distributed system lit tradition I’m using the island nation of Replicos to demonstrate.
Should be of interest for anyone planning distributed topic map stores/distributions.