Olive: Distributed Point-in-Time Branching Storage for Real Systems

This paper describes Olive, the first distributed block storage system to provide consistent pointin-time branching. Point-in-time branching allows users to recursively and quickly snapshot or clone the storage state. It has a wide range of applications including testing new deployments or upgrades without disrupting a running system, quickly provisioning large homogeneous systems, and preserving old versions of data. Olive provides block-level access and strong consistency for broad applicability, allowing it to branch file systems, database systems, and every other storage application that ultimately stores data on block storage. Olive is distributed and replicated to provide fault tolerance and availability. Providing strong consistency for branching in a replicated distributed system is a technical challenge that we address in this work. We evaluate Olive and show that branching typically takes a few tens of milliseconds, and so it has little impact on I/O’s.