Unable to remove one LUN from an existing multi-extent datastore.

Products

• VMware vSphere ESXi

Issue/Introduction

Intend to remove a specific LUN (extent) from a multi-extent VMFS datastore that is currently composed of multiple LUNs or extent.

 

 

Environment

VMware vSphere ESXi 7.x 

VMware vSphere ESXi 8.x 

Cause

• A VMFS datastore can span multiple LUNs (called extents).
• When extents are added, VMFS treats them as a single logical volume, distributing data across them.
• VMFS does not guarantee placement of any specific file or block on a particular LUN; it dynamically allocates blocks across all extents.
• Removing a LUN from a muti-extent datastore is not supported by Broadcom and may lead to the datastore going offline and to data loss. 

Resolution

• Create a new datastore using a single LUN with the required size..
• Migrate all the VMs or VM templates running on the old datastore to the new one.
• Unmount and detach the old datastore from all the ESXi hosts.
• Rescan storage from the ESXi host cluster level.
• Unpresent the LUNs from the hosts at  storage array side.

 

Additional Information

Check this documentation to learn how to properly detach a datastore.