Server Architecture (Marconi)
Marconi provides a driver-based architecture, allowing for different types of message filters and stores. Marconi already ships with a production-ready MongoDB driver, and the team will be adding support for additional message stores during Juno.
Operators can scale out by adding additional API servers and message storage "pools", scale up by increasing the size of an individual pool, or scale out within a single pool by taking advantage of the native scaling capabilities of the message store, if any (e.g., if using MongoDB, an operator may employ it's native ability to shard reads and writes).
Today, a single queue cannot span more than one pool or be moved between pools, but the team is working hard to address these factors during Juno (etherpad).