Storage vMotion or migration fails to convert disk from thick provisioned to thin provisioned when moving within same datastore

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Symptoms:
Storage vMotion or migration fails to convert disk from thick provisioned to thin provisioned.

Environment

VMware vSphere 6.x, 7.x.

Cause

This issue occurs when when performing the Storage vMotion of migration operation within the same datastore.

Resolution

Storage vMotion and storage migration can be used to convert virtual machine disk files from thick to thin provisioned (and vice-versa) only when the files are actually moved from one datastore to another. When the source and destination datastores are the same, no action is performed.

 

For the conversion of the selected disk(s) to take place, the Storage vMotion or migration must involve moving the disk(s) to a different datastore.

Steps

1. Select the VM in the inventory and select Storage only option 
2. Change the storage,  select per disk migration option, under the disk format change the format 
3. Click on finish 

 

Notes:

• Virtual machine disks must be in persistent mode or be raw device mappings (RDMs). For virtual compatibility mode RDMs, you can migrate the mapping file or convert to thick-provisioned or thin-provisioned disks during migration as long as the destination is not an NFS datastore.
• In vSphere 5.0 and later, you can specify thick provisioning on an NFS datastore if the storage array supports it through VAAI. For more information about thick provisioned volume support on your NFS array, contact your storage vendor.

Additional Information