Size of the Datastores getting changed intermittently

Products

• VMware vSphere ESXi

Issue/Introduction

Size of the Datastores getting changed intermittently

• Datastore capacity appears to "shrink" or revert to a previous size automatically.
• vCenter displays intermittent fluctuations between the old LUN size and the newly expanded size.
• Capacity reporting is inconsistent across different views in vSphere Client.

 

Environment

vSphere7.x

vSphere8.x

Cause

When a LUN is expanded on the backend SAN, if a rescan is not performed across all ESXi hosts in the cluster, only the hosts that have refreshed their storage view recognize the new size. vCenter randomly selects a connected host to query for capacity; if it selects a host that has not updated, the old size is displayed.

Resolution

After performing "Rescan Storage" on the Cluster, Datastores showed correct size. A rescan of storage devices is needed when a storage device has been added, removed, expanded or changed from the array.

To resolve this, please perform a storage rescan across the entire cluster:

1. Log in to the vSphere Client.
2. Select the Cluster in the inventory.
3. Right-click the Cluster and select Storage > Rescan Storage.
4. Ensure both Scan for new storage devices and Scan for new VMFS volumes are checked.
5. Click OK and verify the task completes for all hosts in the cluster.
6. If a specific host fails to update, log in via SSH and run: esxcli storage core adapter rescan --all