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Meaningful availability

Dan Ardelean
Philipp Emanuel Hoffmann
Tamás Hauer
17th USENIX Symposium on Networked Systems Design and Implementation (NSDI'20) (2020)
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Accurate measurement of service availability is the cornerstone of good service management: it quantifies the gap between user expectation and system performance, and provides actionable data to prioritize development and operational tasks. We propose a novel metric, user-uptime, which is event- based but is time-sensitive and which approximates aggregated user-perceived reliability better than current metrics. For a holistic view of availability across timescales from minutes to months or quarters, we augment user-uptime with a novel aggregation and visualization paradigm: windowed uptime. Using an example from G Suite we demonstrate its effectiveness in differentiating between unreliability caused by flakiness and an extended outage.