A Grafana DatasourceNoData notification means an alert evaluation returned no series or only null values—not a measured 5xx rate of zero. Grafana’s default No Data behavior creates a separate alert instance for that condition. A four-hour cadence alone does not reveal whether it is repeating the same firing alert or reporting a new No Data transition; check the alert’s state history and the notification policy that matches it.
What DatasourceNoData means
When an alert evaluation has no data, Grafana can put the rule into the No Data state and create a separate alert instance labeled alertname: DatasourceNoData. It is distinct from the original 5xx-rate alert and may not carry all of that rule’s labels. The original rule can therefore appear healthy even while an evaluation has no usable result for the 5xx query. See Grafana’s guidance on No Data and error states.
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No series or all-null values are not equivalent to a zero rate. A zero is a result; no data means Grafana cannot determine the rate from that evaluation.
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1Fix the driver behind crashes, sound loss and screen glitches2Clear out junk files and repair common Windows errors3Scan for outdated or missing drivers - takes under a minuteWhy the notification may arrive every four hours
Grafana has separate settings for evaluating a rule and notifying you. The evaluation group interval determines how often the query runs. The pending period determines how long a condition must persist before the alert changes state. The notification repeat interval can send another notification while an alert remains firing. These are different timers, so the four-hour interval does not, by itself, identify the cause. Grafana explains these timing controls in its alert rule evaluation documentation and notification documentation.
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Use the event history to distinguish a repeated notification for one continuously firing DatasourceNoData instance from separate No Data state transitions. Then inspect the notification policy matched by that instance. Because the special alert has different labels from the original rule, it may follow a different route or repeat interval. Grafana documents policy matching in its notification policy guide.
Trace the cause in this order
- Open the alert state history. For each four-hour event, note whether it is a repeated notification or a new state change. Record the alert name, rule UID, data source UID, and timestamps.
- Inspect the evaluated result at an event time. Check whether the query returned no series, only null values, or a numeric result. Review its labels, time range, aggregation, and whether the numerator or denominator disappears when traffic is absent. A successful query execution can still produce no usable series.
- Check the notification route for the special alert. Find the policy matched by
DatasourceNoDataand review its repeat interval and labels. Do not assume the original 5xx alert’s route applies. - Review the rule’s timing separately. Check the evaluation group interval and pending period, then compare those settings with the event timestamps and the matched policy’s repeat interval.
The title alone does not establish a particular PromQL defect or notification configuration. The query, rule type, Grafana version, state history, and policy determine which explanation applies. UI wording and behavior can vary by version and by whether the rule is Grafana-managed or data source-managed.
Decide what missing data should mean
Choose the no-data behavior according to whether missing telemetry is itself actionable, whether absence truly means zero, and whether a brief gap should preserve the prior state. Grafana’s documented options are:
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- No Data: Keep the missing result visible as a separate No Data alert. This is the default behavior described by Grafana.
- Alerting: Treat the missing result as an alerting condition.
- Normal: Treat it as normal. This can suppress a no-data alert, but it can also hide telemetry loss.
- Keep Last State: Preserve the previous alert state while data is missing.
Find the rule’s no-data response setting in the alert rule configuration; the exact UI path and wording depend on Grafana version and rule type. Grafana describes these choices in its missing-data guidance.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.When to make an empty Prometheus result zero
If the absence of matching series genuinely means a zero 5xx rate—for example, when there were no requests and that is the intended interpretation—you can make a Prometheus query return zero when its main expression returns nothing. Grafana’s example is:
your_metric_query OR on() vector(0)
Use this only when absence should count as zero. If missing metrics could indicate a broken scrape, unavailable data source, or other telemetry loss, converting absence to zero can conceal an operational problem. In that case, retain a missing-data signal and route it to the people responsible for monitoring the telemetry. Grafana gives this Prometheus example in its No Data documentation.
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