Constant burn anomaly

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The Constant burn anomaly identifies an SLO objective that continuously consumes error budget for an unusually long time. It can expose an objective that is too strict or an SLI that does not represent the intended user experience.

How detection works

Nobl9 observes the objective's instantaneous burn rate. A continuous sequence above the configured burn threshold starts the observation period. A point at or below the threshold interrupts the sequence.

With the defaults, the anomaly is detected after one week of uninterrupted burn. Once detected, it resolves after 30 minutes without another burning point. A new burning point during that cooldown extends the open anomaly.

Continuous burn detectionBurn remains above the default threshold for one week, then the anomaly resolves after 30 minutes at the threshold.

Instantaneous burn rate

Setting	Automatic default
Burn threshold	0
Observation period	1 week
Cooldown	30 minutes

An anomaly is not proof of a configuration error

A real incident can produce sustained burn. Compare the annotated period with service incidents and telemetry before changing the SLO.

Example

Suppose an objective burns continuously for seven days. Nobl9 creates one Constant burn annotation. If the burn stops for 20 minutes and then resumes, the annotation remains open because the 30-minute cooldown did not complete. If the objective stays below the burn threshold for the full cooldown, the annotation is resolved.

What to investigate

For a threshold SLO, check whether the objective target is too strict. For a ratio SLO, compare the numerator and denominator scopes and confirm that the target matches historical performance.

Use SLI Analyzer to evaluate alternative targets and queries. See Data anomaly troubleshooting for more checks.

API access

Query Constant burn anomalies with the Anomalies API and anomalyTypes: ["ConstantBurn"]. Retrieve continuously detected annotations with the Annotations API and category=ConstantBurnAnomaly.