Alfred Fuller, Matt Wilder
For the first three years of App Engine, the health of the datastore was tied to the health of a single data center. Users had low latency and strong consistency, but also transient data unavailability and planned read-only periods. The High Replication Datastore trades small amounts of latency and consistency for significantly higher availability. In this talk we discuss user-facing and operational issues of the original Master/Slave Datastore, and how the High Replication Datastore addresses these issues.