Cannot power on or consolidate snapshots on a VM residing on a full LUN

Products

• VMware vSphere ESXi

Issue/Introduction

In the case that snapshots fill all remaining space on the VMs backing LUN,  we will be unable to write to the disk for consolidation.

You may get the error when consolidating: 

An error occurred while consolidating disks: There is not enough space on the file system for the selected operation

 

This may also cause the VM to be unable to power on. 

Environment

VMware vSphere 8.0.x

VMware vSphere 7.0.x

Cause

To consolidate snapshots vCenter requires a bit of overhead space. Without space on the LUN, vCenter cannot write to the appropriate files for consolidation, thus causing it to throw the error above.  

Resolution

To correct this you can do one of the following: 

• Reduce space usage on the LUN 
  • You can migrate some VMs to a different datastore
  • You can remove iSOs and Templates on that LUN 
• Increase the space on the LUN
  • You can extend the backend array and then Extend the vmfs datastore through vCenter
  • Or, if you cannot extend the backend LUN you can add another extent.
    • NOTE SIOC does not support multiple extents. If you need to add an extent you will need to disable SIOC on the LUN.

Additional Information

For information on datastore consolidation issues when the backing LUN is not full see Consolidating/Committing snapshots in VMware ESXi