The virtual machines hosted on vSAN datastore are reporting almost double the allocated size.

Products

• VMware vSphere ESXi

Issue/Introduction

• Discrepancy noticed between VM used storage and allocated disk space.
• Few virtual machines are reporting storage usage of half the allocated space.
• Few virtual machines are reporting storage usage of double the allocated space.
• No virtual machine snapshots present and do not contribute to used space.

Environment

ESXi 8.0 U3
vSAN 8.0.U3

Cause

Disk provisioning type is thick where the used storage space is reporting double the allocated size. Virtual machine storage policy is "Datastore Default"
Disk provisioning type is thin where the used storage space is reporting half the allocated size.  Virtual machine storage policy is "vSAN Default Storage Policy"

Resolution

Change the virtual machine's storage policy to "vSAN Default Storage Policy". Steps to change virtual machine's storage policy :

1. Locate the Virtual Machine: In the vSphere UI, navigate to the virtual machine whose policy you want to modify.
2. Open Configure Tab: Click on the "Configure" tab for the virtual machine.
3. Access Policies: Click on "Policies".
4. Edit VM Storage Policies: Click on "Edit VM Storage Policies".
5. Select the ""vSAN Default Storage Policy" from the dropdown menu to apply it to all virtual machine objects.
6. Click "OK" to save the changes and assign the storage policy.