zeroedthick (default) – Space required for the virtual disk is allocated during creation. Any data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine.
eagerzeroedthick – Space required for the virtual disk is allocated at creation time. In contrast to zeroedthick format, the data remaining on the physical device is zeroed out during creation. It might take much longer to create disks in this format than to create other types of disks. Reason to use this disk is that has a slight performance gain as compared to zeroedthick disks.
thick – Space required for the virtual disk is allocated during creation. This type of formatting doesn’t zero out any old data that might be present on this allocated space. A non-root user is not allowed to create this format.
thin – Thin-provisioned virtual disk. Unlike with the thick format, space required for the virtual disk is not allocated during creation, but is supplied, zeroed out, on demand at a later time.
rdm – Virtual compatibility mode raw disk mapping.
rdmp – Physical compatibility mode (pass-through) raw disk mapping.
2gbsparse – A sparse disk with 2GB maximum extent size. The VMDK is saved in split 2GB files.