We are using Avamar to backup do our VM image backups and I have come up with a question about the impact of the disk provisioning type and how it affects Avamar's backups (specifically the size). We are running ESXi version 5.0 Update 3.
We currently provision our disks on our VMs as "thick provision, lazy zeroed". First of all what is the recommended provisioning method "thick provisioned, lazy zeroed" or "thick provisioned, eager zeroed". I understand that the eager zeroed will write zeros on each block as the disk at the same time the disk is provisioned while the lazy zeroed will write a zero at write time. Also, how does this impact the size of an image backup. Do the disks that are eager zeroed take up more space or less on backups?