Create a Trigger to Notify Cluster Administrators when Free Space Runs Low

The following steps create a trigger to alert Cloudera Manager cluster administrators when free space on the Application Block Device has fallen below a specific threshold.

  1. Log in to Cloudera Manager and go to the CDSW service page.
  2. Click Create Trigger.
  3. Give the trigger a name.
  4. Modify the Expression field to include a condition for the trigger to fire. For example, if the trigger should fire when unallocated disk space on the Application Block Device falls below 250GB, the expression should be:
    IF (select capacity_free where mountpoint="/var/lib/cdsw" and category=FILESYSTEM and hostname="<CDSW_Master_hostname>" and LAST (capacity_free) < 250GB) DO health:concerning
    On the right hand side of the page, you should see a preview of the query you have entered and a chart that displays the result of the query as in the following sample image. Note that if the query is incorrect or incomplete you will not see the preview on the right.

  5. Click Create Trigger. If you navigate back to the CDSW service page, you should now see the new trigger in the list of Health Tests.
    For more details about Triggers, refer the following topic in the Cloudera Manager documentation: Triggers.