Time, Progress and the Cost of Interruption in Resilient Systems

Abstract

Resilience is commonly evaluated through availability, fault tolerance, recovery time and the frequency of failure. These measures describe whether service remains operational and how quickly execution can be restored, but they do not fully describe the fate of work already in progress when an interruption occurs. This paper proposes that preservation of valid committed progress is a fundamental property of resilient systems. It introduces an interruption profile comprising additional elapsed time, loss of valid progress and additional recovery effort. Progress is not assumed to be a universal scalar. It is treated as a domain-specific set or partial ordering of valid outcomes that remain identifiable and safely reusable after the execution context that produced them has disappeared. The paper also distinguishes a recovery knowledge deficit from the effort required to resolve it and from recovery debt that persists when recovery obligations are repeatedly externalised to operators. The model is applied comparatively to restart, checkpointing, idempotent activities, transactional messaging, saga coordination and durable workflow execution. The comparison shows that rapid restoration of execution does not by itself preserve business outcomes or establish the next safe action. The paper further identifies limitations involving rollback, expiring outcomes, planned suspension, irreversible side effects and the ongoing cost of resilience mechanisms. From this analysis, the paper derives the following progress-preservation principle: In a resilient system, interruptions should cost time, not progress. The principle is an architectural objective rather than a claim that interruption can be made cost-free or a prescription for a particular technology. Keywords: resilience, durable execution, progress preservation, recovery debt, idempotency, distributed systems, workflow orchestration, interruption cost