Using Gossip Protocols for Failure Detection, Monitoring, Messaging and Other Good Things
Monday, November 14, 2011 at 9:15AM 
When building a system on top of a set of wildly uncooperative and unruly computers you have knowledge problems: knowing when other nodes are dead; knowing when nodes become alive; getting information about other nodes so you can make local decisions, like knowing which node should handle a request based on a scheme for assigning nodes to a certain range of users; learning about new configuration data; agreeing on data values; and so on.
How do you solve these problems?
A common centralized approach is to use a database and all nodes query it for information. Obvious availability and performance issues for large distributed clusters. Another approach is to use Paxos, a protocol for solving consensus in a network to maintain strict consistency requirements for small groups of unreliable processes. Not practical when larger number of nodes are involved.
So what's the super cool decentralized way to bring order to large clusters?
