Datastore usage on disk alarm behavior and troubleshooting

Products

• VMware vCenter Server

Issue/Introduction

The "Datastore usage on disk" alarm triggers in vCenter Server when storage consumption exceeds preconfigured thresholds (Warning: 75%; Critical: 85%). This article outlines how to validate these alerts, resolve capacity issues, and address "stale" alarm states.

Environment

VMware vCenter Server 7.x, 8.x
VMware vSphere ESXi 7.x, 8.x

Cause

Default vCenter alarm definitions trigger alerts. If storage usage is below the configured thresholds, the alarm may be "stale" due to a known desynchronization issue in vCenter 7.x/8.x.

Resolution

Step 1: Validate Usage

1. Log in to the vSphere Client.
2. Select the datastore and navigate to the Monitor > Performance tab to verify current usage.
3. If usage is above 75%, proceed to Step 2.

Step 2: Clear Space

• Delete unnecessary ISO files, templates, or unused snapshots.
• Migrate non-critical virtual machines to datastores with sufficient capacity using Storage vMotion.
• If utilization remains high, expand the datastore capacity at the storage array level and increase the VMFS datastore capacity.

Step 3: Resolve Stale Alarms

If usage is below thresholds but the alarm persists:

1. Navigate to vCenter Server > Configure > Alarm Definitions.
2. Locate the Datastore usage on disk alarm.
3. Disable the alarm definition and save.
4. Re-enable the alarm definition.

Step 4: Modify Thresholds

If the default thresholds do not match environment requirements:

1. Navigate to Alarm Definitions as described above.
2. Edit the Datastore usage on disk alarm to adjust the Warning and Critical percentage values.

Additional Information

Additional Information

• For help with log retrieval, see Retrieving vCenter Server logs.
• To speak with a support representative, see Contact Support.