The rules are stored within the data source. In a distributed architecture, they can scale horizontally to provide high-availability. For more details, refer to [alert rule types](ref:alert-rules).
We recommend using [Grafana-managed alert rules](ref:configure-grafana-managed-rules) whenever possible and opting for data source-managed alert rules when scaling your alerting setup is necessary.
> Rules from a Prometheus data source appear in the **Data source-managed** section of the **Alert rules** page when [Manage alerts via Alerting UI](ref:shared-configure-prometheus-data-source-alerting) is enabled.
>
> However, Grafana can only create and edit data source-managed rules for Mimir and Loki, not for a Prometheus instance.
For more information, refer to the [Mimir Ruler API](/docs/mimir/latest/references/http-api/#ruler) or [Loki Ruler API](/docs/loki/latest/api/#ruler).
- **Mimir** - use the `/prometheus` prefix. The Prometheus data source supports both Grafana Mimir and Prometheus, and Grafana expects that both the [Query API](/docs/mimir/latest/operators-guide/reference-http-api/#querier--query-frontend) and [Ruler API](/docs/mimir/latest/operators-guide/reference-http-api/#ruler) are under the same URL. You cannot provide a separate URL for the Ruler API.
- **Loki** - The `local` rule storage type, default for the Loki data source, supports only viewing of rules. To edit rules, configure one of the other rule storage types.
Note that if you delete an alert resource created in the UI, you can no longer retrieve it.
To backup and manage alert rules, you can [provision alerting resources](ref:shared-provision-alerting-resources) using options such as configuration files, Terraform, or the Alerting API.
Define a query to get the data you want to measure and a condition that needs to be met before an alert rule fires.
{{% admonition type="note" %}}
By default, new alert rules are Grafana-managed. To switch to **Data source-managed**, follow these instructions.
{{% /admonition %}}
1. Select a Prometheus-based data source from the drop-down list.
You can also click **Open advanced data source picker** to find more options.
1. Enter a PromQL or LogQL query, including the alert condition.
1. In the **Rule type** option, select **Data source-managed**.
1. Click **Preview alerts**.
## Set alert evaluation behavior
Use [alert rule evaluation](ref:alert-rule-evaluation) to determine how frequently an alert rule should be evaluated and how quickly it should change its state.
1. Select a namespace or click **+ New namespace**.
1. Select an evaluation group or click **+ New evaluation group**.
If you are creating a new evaluation group, specify the interval for the group.
The [pending period](ref:pending-period) is the period in which an alert rule can be in breach of the condition until it fires.
Once a condition is met, the alert goes into the **Pending** state. If the condition remains active for the duration specified, the alert transitions to the **Firing** state, else it reverts to the **Normal** state.
## Configure labels and notifications
Add [labels](ref:alert-rule-labels) to your alert rules to set which [notification policy](ref:notification-policies) should handle your firing alert instances.
All alert rules and instances, irrespective of their labels, match the default notification policy. If there are no nested policies, or no nested policies match the labels in the alert rule or alert instance, then the default notification policy is the matching policy.
1. Add labels if you want to change the way your notifications are routed.
Add custom labels by selecting existing key-value pairs from the drop down, or add new labels by entering the new key or value.
