ISO/IEC 19086-2:2018 Cloud computing – service level agreement (SLA) framework – part 2: Metric model

Summary

The measurement of cloud service properties, critical for cloud service level agreements (SLAs), faces several challenges that hinder the adoption and effectiveness of cloud services. Metrics are often described in natural language, which can be unclear, ambiguous, and hard to compare or implement. Key issues include:

1. Clarity: Metrics may be incomplete, ambiguous, illogical, or self-contradictory. For instance, providers may mislead or manipulate definitions of ‘availability’.
2. Comparability: Inconsistent metric definitions make comparing service levels across different providers difficult.
3. Implementation: Some metrics are impractical or impossible to measure accurately, making it hard to verify if service levels are met.

This document addresses these concerns by providing a metric model that defines conditions and rules for measuring and interpreting results. It aims to:

1. Clarity: Remove ambiguities in metric definitions.
2. Comparability: Facilitate comparing metrics and service level objectives (SLOs).
3. Implementation: Support the development of measurement tools and revision of metrics to ensure they are practical.

While the focus is on metrics for cloud SLAs, the document’s structured approach can also be applied to cloud service metrics (CSMs) used for internal monitoring by providers and potentially to non-CSMs.