Availability Without a Model: On the Semantic Fragmentation of Operational Metrics

Availability is widely used as a primary managerial indicator in operational and distributed information systems. Yet in practice, availability metrics often originate from heterogeneous observational layers — infrastructure state, service behavior, or business-level functionality — without an explicit cross-layer model. This paper argues that such usage produces semantic fragmentation: numerically stable indicators that lack declared structural equivalence. A minimal formalization distinguishes infrastructure (I), service (S), and business (B) state spaces and shows that equality of availability values does not imply informational identity. Situating operational monitoring within the framework of Coherent Observational Epistemology (COE), the paper interprets model-free availability as a case of inter-local inference without verified structural alignment. The Unified Availability Model (UAM) is presented as an implementable example of model-based availability, restoring cross-layer transparency and comparability.