Attempts to extend the size of an EagerZeroedThick VMDK from the vSphere Client might result in a LazyZeroedThick VMDK

Products

• VMware vSphere ESXi

Issue/Introduction

When you attempt to extend the size of an EagerZeroedThick VMDK from the vSphere Client, the extended part of the disk becomes LazyZeroedThick.

Environment

VMware vSphere ESXi 6.5
VMware vSphere ESXi 6.7
VMware vSphere ESXi 7.x
VMware vSphere ESXi 8.x

Resolution

Workaround:

1) If you need to extend the VMDK and want the VMDK to be EagerZeroedThick, run this command:

~ # vmkfstools -X 6G -d eagerzeroedthick /vmfs/volumes/<datastorename>/<name>.vmdk
Grow: 100% done.
All data on /vmfs/volumes/<datastorename>/<name>.vmdk will be overwritten with zeros from sector <8388608> onwards.
Zeroing: 100% done.

Note: -X 6G denotes the extended size of the datastore - in this case 6 GB.

If you extend the disk by using UI, you have no control over all the options to extend the disk. As a result, the EagerZeroedThick VMDK automatically becomes LazyZeroedThick.

For further information, see: Extending a Virtual Disk

 

2) If you have already extended an EagerZeroedThick VMDK via the UI and it now reports LazyZeroedThick format, convert the VMDK back to EagerZeroedThick by running this command:

vmkfstools --eagerzero /vmfs/volumes/<datastorename>/<name>.vmdk

 For additional information see: Converting a Zeroedthick Virtual Disk to an Eagerzeroedthick Disk

For more information, see Determining if a VMDK is zeroedthick or eagerzeroedthick (1011170)