PhD Defense: Dynamic Upgrades for High Availability Systems

In this thesis we show that it is possible to build general-purpose frameworks for efficient, on-line data transformation in support of flexible system services, especially dynamic software updates (DSU). Our approach generalizes some of the ideas from prior work on DSU, making those ideas applicable to a greater number of situations. In particular, we generalize DSU's notion of in-memory state transformation---normally used to upgrade run-time state to be consistent with the new software---so that it can be applied to data not necessarily stored in memory, and for services other than DSU.
To support this thesis, we present three artifacts. First, we present C-strider, a generic type-aware C heap traversal framework. C-strider constitutes a flexible, easy-to-use framework with which developers can program specific and reusable services that have a heap traversal at their core, e.g., serialization, profiling, invariant checking, and state transformation (in support of DSU). C-strider supports both parallel and single-threaded heap traversals. Second, we present KVolve, a data transformation service for NoSQL databases. KVolve is notable in that transformations are carried out on-line and on-demand, as data is accessed, rather than off-line and all at once, which would reduce service availability. Experiments with on-line upgrades of services using KVolve show little overhead during normal operation, and only brief pauses at update-time. Finally, we present Morpheus, a dynamically updatable software-defined network (SDN) controller. Morpheus' architecture is fundamentally distributed, with each service running as a separate process that accesses a shared KVolve instance. We show that Morpheus can update multiple controller applications without loss of availability or degradation of performance.
Examining Committee:
Committee Chair: - Dr. Michael Hicks
Co-Chair: - Dr. Jeffrey Foster
Dean's Representative: - Dr. Rajeev Barua
Committee Member(s) - Dr. Alan Sussman
- Dr. Tudor Dumitras