system-availability quantifies the proportion of time a system remains operational within a defined period, expressed as a ratio (e.g., 99.9%) or a fraction of uptime versus total time. It is computed from uptime records maintained by monitoring infrastructure and enforced through service-level agreements (SLAs) that define acceptable thresholds and the consequences of shortfall. Its persistence mechanism is the continuous logging of operational state by monitoring agents, aggregated into availability calculations over fixed windows, and codified in contractual SLA commitments. [formal: presentia systematis | substrate: behavior | horizon: hours | explicit: yes | epoch: 0.01]
Accepted ontology entry
system-availability
system-availability quantifies the proportion of time a system remains operational within a defined period, expressed as a ratio (e.g., 99.9%) or a fraction of uptime versus total time. It is computed from uptime records maintained by moni…
Definition
Why it is in scope
A human-made reliability metric expressing the proportion of time a system is operational and accessible when needed, typically calculated as MTBF/(MTBF+MTTR). Built to persist through mathematical modeling and engineering practice for designing SLAs, capacity planning, and evaluating redundancy strategies in service architectures.
Names and aliases
- system-availabilityen · CANONICAL
Relations from this entry
- cmrwiv1rn00a8soacg5vdpiogINSTANCE_OF →
system-availability is a specific kind of metric: it quantifies the proportion of time a system remains operational. A competent speaker would call it 'a metric' (not 'a measurement' — measurement is the act, not the value). Direction: specific→general.
- cms7wyk72004ph6s8d82lhwqlSERVES →
system-availability quantifies uptime proportion, and this quantification exists for the sake of reliability engineering — to set SLAs, track trends, and guide improvement efforts. The designed purpose of measuring availability is to serve reliability's operational goals.
Relations to this entry
No accepted relations in this direction.
Record identity
- Created
- Aug 7, 2026, 9:49 PM UTC
- Content hash
- a427ecd8618da303ab303c4ebf357c571b9f2d43b7b4bf294f776433e456d611