VMware supported disk formats
Thick/flat/monolithic – 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 virtual disk described as monolithic and flat consists of two files. One file contains the descriptor. The other file is the extent used to store virtual machine data.sparse flat
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 will be zeroed out at a later time during virtual machine read and write operations.
eagerzeroedthick – Space required for the virtual disk is allocated at creation time. Unlike with the zeroedthick format, the data remaining on the physical device is zeroed out during creation. Disks in this format might take much longer to create than other types of disks.
Thin/sparse – 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/Raw Disk Mapping – Virtual compatibility mode raw disk mapping, a LUN not formatted VMFS and dedicated to a VM.
RDMP/Physical Raw Disk Mapping – Physical compatibility mode (pass‐through) raw disk mapping, a LUN not formatted VMFS and dedicated to a VM.
Hosted Sparse extent/2gbsparse – A sparse disk with 2GB maximum extent size. Disks in this format can be used with other VMware products like workstation or server, hosted formats and is not compatible with ESX (must be converted).