A New Approach to Proactive Recovery

Recent papers propose asynchronous protocols that can tolerate any number of faults over the lifetime of the system, provided that at most f nodes become faulty during a given window of time. This is achieved through the so-called proactive recovery, which consists of periodically rejuvenating the system. Proactive recovery in asynchronous systems, though a major breakthrough, has some limitations which we identified in a recent work. In fact, proactive recovery protocols typically require stronger environment assumptions (e.g., synchrony, security) than the rest of the system. In this paper, we take this in consideration and propose a new approach to proactive recovery that is based on an architecturally hybrid distributed system model. In this context, we present a secure real-time distributed component — the Proactive Recovery Wormhole (PRW) — that aims to execute, in a more dependable and effective way, proactive recovery protocols. We also briefly show how PRW can be used in practice to enhance the dependability of an existent proactive recovery based system.