Pronto: A Fast Failover Protocol for Off-the-shelf Commercial Databases

high availability, database failover, database replication, fault tolerance, transaction processing, three-tier architectures Enterprise applications typically store their state in databases. If a database fails, the application is unavailable while the database recovers. Database recovery is time consuming because it involves replaying the persistent transaction log. To isolate end-users from database failures, we introduce Pronto, a protocol to orchestrate the transaction processing by multiple, standard databases so that they collectively implement the illusion of a single, highly-available database. The key challenge in implementing this illusion is to enable fast failover from one database to another so that database failures do not interrupt the transaction processing. We solve this problem with a novel replication protocol that handles non-determinism without relying on perfect failure detection.