Use separate metric rules when conditions must alert independently

Source facts

An Azure Monitor metric alert can contain up to five conditions, combined with AND: every condition must be met to fire, and a fired alert resolves when any condition stops being met. This differs from a multi-resource rule, which evaluates each resource separately and allows only one condition. Multi-resource targets must share a resource type and Azure region. Microsoft Learn.

Applicability

Review this distinction when simplifying a collection of alert rules or when an operator expects either of two symptoms to trigger independently. A single rule is not automatically equivalent to the separate rules it replaces. Confirm that the chosen resource and dimension combination is supported before implementation.

DSE recommendation

Write the required Boolean behavior before consolidating metric alert conditions into one rule. Ask the service owner whether the requirement means both symptoms together or either symptom on its own. Keep independent conditions in separate rules when that is the intended outcome. For a correlated condition set, document why losing any one condition should end the combined alert rather than leave the incident assumption unchanged.

Verification

Use an approved test plan covering neither condition, each condition alone and both together. Record the actual alert behavior and the transition when one condition clears. For a multi-resource design, compare outcomes separately for each target. Preserve the expected truth table with the rule configuration so later consolidation work does not silently change the detection requirement.

Official references

Microsoft Learn: Multiple time series in a metric alert rule. Source reviewed September 9, 2026.