Eager Zeroed Thick disks cannot be converted back to Thick using Storage vMotion, Cloning, Migration, or vmkfstools

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Symptoms:

When a virtual disk is Eager Zeroed Thick for a Virtual Machine and you:

• Deploy the Virtual Machine from a Template
• Clone the Virtual Machine
• Clone the Virtual Disk
• Initiate a Storage vMotion of the Virtual Machine or its disk
• Initiate an offline datastore Migration of the Virtual Machine or its disk

Selecting Thick as the destination format still results in an Eager Zeroed Thick disk at the destination. The vSphere Client, vSphere Web Client, and vmkfstools do not return errors despite the selected destination format not taking effect.

Environment

VMware vSphere ESXi 6.5
VMware vCenter Server 5.5.x
VMware vCenter Server 6.0.x
VMware vSphere ESXi 7.0.0
VMware vCenter Server 5.1.x
VMware vSphere ESXi 5.0
VMware vSphere ESXi 5.1
VMware vSphere ESXi 6.7
VMware vCenter Server 5.0.x
VMware vSphere ESXi 6.0
VMware vSphere ESXi 5.5

Resolution

This is expected behavior. You cannot directly clone or migrate an Eager Zeroed Thick format disk to Thick (Lazy Zeroed Thick).

As a workaround, you can clone or migrate the Eager Zeroed Thick disk to Thin, then once again from Thin to Thick. This can be performed live, via Storage vMotion.

For additional information or instructions on performing migrations, see Migrating virtual machines (1017769).

Note: If a template or source machine disk was previously copied using more a traditional means, such as via Copy-DatastoreItem in PowerCLI, the Datastore Browser, or simply via copy commands in a shell session, this may be a cause as to why source files are Eager Zeroed Thick. Converting the source template or Virtual Machine to the desired format first can save deployment efforts, time, and storage.

Additional Information

Migrating virtual machines
Storage vMotion、クローン作成、移行、または vmkfstools を使用して Eager Zeroed Thick ディスクを Thick に戻す変換ができない
使用 Storage vMotion、克隆、迁移或 vmkfstools 无法将置零厚磁盘转换回厚格式