Last week I attended interesting breakfast talk by Doug Terry, principal researcher from Microsoft Research Silicon Valley and I think it is pretty cool talk B-). The talk itself is about other consistency types which lie between Strong and Eventual Consistency, and how the additional consistency types are (practically) used through simple pseudo-code of baseball game. And this is the first of two planned posts for this topic.
Let’s start with two most basic consistency model (which we usually learn in our first Distributed System course/module in University): Strong Consistency and Eventual Consistency.
In Strong Consistency, every node in distributed system will always see the same and latest view after a specific node update the data. This consistency type sacrifices performance and availability in order to ensure consistent view across the node in the distributed system since it is expensive in term of network and computing resources needed to maintain the consistency. Example of system that uses Strong Consistency is Windows Azure. Strong Consistency is desirable within a data center however performance and availability concerns start raising in geo-replication service that spans in multiple-data center.