Not able to migrate VM from one cluster to another cluster

Products

• VMware vSphere ESXi
• VMware vCenter Server

Issue/Introduction

When attempting to perform a vMotion that includes both compute and storage resources, you're unable to perform the vMotion due to an error "Insufficient disk space on datastore 'ExampleDatastore1'".

Environment

VMware vCenter Server 6.x
VMware vCenter Server 7.x
VMware vCenter Server 8.x
VMware ESX 6.x
VMware ESX 7.x
VMware ESX 8.x

Cause

There isn't enough free space on the target storage device/datastore to perform the storage vMotion of the VM.

Resolution

Check the amount of space the VM is occupying as opposed to what it is assigned.  For instance if you have a VM with a single VMDK of a 100GB and 5 snapshots, the actual consumed size can be much larger.

Other overhead for the VM may also need to be considered in preparing the vMotion.