A new preview release of the MongoDB controller for Azure is available. This release includes support for replica sets, and over the coming months, we’ll be adding support for MongoDB’s sharding facilities. We’ll also be working to more tightly integrate MongoDB with the features of Azure platform. Each member of a replica set is hosted by an instance of an Azure worker role, so the size of the replica set is determined by the number of instances configured for the the replica set worker roles. Each replica set worker role creates a child process to run the mongod server process. The controller defines an Azure worker role which represents a MongoDB cluster.