---
title: Monitoring Available Disk Space
description: >-
  Step-by-step guide to create monitors for available disk space that alert when
  free disk space falls below a specified percentage threshold.
breadcrumbs: Docs > Monitors > Monitor Guides > Monitoring Available Disk Space
---

# Monitoring Available Disk Space

A common system metric to monitor is the available disk space on a given system or host. This guide helps you create a monitor that alerts you when free disk space for a host falls below 10% for any host reporting to Datadog.

To create the monitor for available disk space:

1. In the navigation menu, click **Monitors**.

1. Click **New Monitor**.

1. Select **Metric** as the monitor type.

   1. In the **Define the metric** section, use `system.disk.free` for the metric and select `host` for **avg by**. This is Query a.

   1. Click **Add Query**. For this metric, use `system.disk.total` for the metric and use `host` for **avg by**. This is Query b.

   1. In the formula that appears, replace `a + b` with `a/b*100`.

      {% image
         source="https://docs.dd-static.net/images/monitors/guide/monitoring_free_disk_space.70d6f8be88121b620d1af18a1782e310.png?auto=format&fit=max&w=850 1x, https://docs.dd-static.net/images/monitors/guide/monitoring_free_disk_space.70d6f8be88121b620d1af18a1782e310.png?auto=format&fit=max&w=850&dpr=2 2x"
         alt="Query definition of system.disk.free and system.disk.total with formula a/b*100" /%}

   1. Under **Evaluation Details**, choose your desired evaluation interval.

      {% image
         source="https://docs.dd-static.net/images/monitors/guide/monitoring_free_disk_space_alert_criteria.e9bf91859616ccc09cbaafe6c1728a17.png?auto=format&fit=max&w=850 1x, https://docs.dd-static.net/images/monitors/guide/monitoring_free_disk_space_alert_criteria.e9bf91859616ccc09cbaafe6c1728a17.png?auto=format&fit=max&w=850&dpr=2 2x"
         alt="Alert criteria configuration set to below threshold, with a value of 10." /%}

1. Under **Set alert conditions**, select **below** from the threshold options and enter `10` in **Alert threshold** field.

1. In **Configure notifications & automations**, give your monitor a name, then specify the notification message. Include relevant details and a meaningful message template. For example:

   ```
     {{#is_alert}} Alert: Free disk space is below {{threshold}}% on {{host.name}}. {{/is_alert}}
     {{#is_warning}} Warning: Free disk space is below {{warn_threshold}}% on {{host.name}}. {{/is_warning}}
     Disk space available: {{value}}%
   ```

1. Click **Create** to save the monitor.