0005 Thick Eager Zeroed: The negative impact of using "Thick Eager Zeroed" disk provisioning for a Virtual Machine VMDK. The negative effect is that it takes too long to provision the VMDK for a VM, because it zero all blocks first and it has an extended period IO hit on the storage system. The whole disk space is taken and not available for use by other virtual machines.
On the other hand, the eager zeroed thick disks will get you the best performance even in all flash arrays for all types of write workloads. Also, a great performance benefit to the VM because it doesn’t have to zero a block before it can be written to.