Eager zero provisioned disk changes to Lazy zero provisioned disk

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:
When you expand an Eager zero thick provisioned disk it changes to Lazy zero thick provisioning disk.

 

 

Environment

VMware vSphere ESXi 6.0
VMware vSphere ESXi 6.5
VMware vSphere ESXi 6.7
VMware vSphere ESXi 7.0

Cause

This issue occurs when the default Thick Provision Eager Zeroed is created the data remaining on the physical device is zeroed out when the virtual disk is created, when you expand the disk it will not zero out the blocks from the storage array this changes the eager zeroed disk to lazy zeroed thick provisioned disk.

 

 

Resolution

This issue has been addressed in ESXi 8.0 or later.

Zero the disk again:

vmkfstools --eagerzero /vmfs/volumes/myVMFS/VMName/disk.vmdk
https://techdocs.broadcom.com/us/en/vmware-cis/vsphere/vsphere/7-0/vsphere-storage-7-0/using-vmkfstools-in-vsphere/vmkfstools-options/virtual-disk-options-of-vsphere-vmkfstools-command/converting-a-zeroedthick-virtual-disk-to-an-eagerzeroedthick-disk.html

Another option is to do a storage vMotion of the affected disk and it will change back to Eager Zeroed disk again.

Additional Information

Impact/Risks:
Shared VMDKs used in cluster configurations such as WSFC must be in the eager zeroed thick format.
If such a VMDK is expanded and becomes lazy zeroed thick, it must be converted back to eager zeroed thick using the vmkfstools --eagerzero command.