Storage devices that your host supports can use either the master boot record (MBR) format or the GUID partition table (GPT) format.
With ESXi 5.0 and later, if you create a new VMFS5 datastore, the device is formatted with GPT. The GPT format enables you to create datastores larger than 2TB and up to 64TB for a single extent.
VMFS3 datastores continue to use the MBR format for their storage devices. Consider the following items when you work with VMFS3 datastores:
For VMFS3 datastores, the 2TB limit still applies, even when the storage device has a capacity of more than 2TB. To be able to use the entire storage space, upgrade a VMFS3 datastore to VMFS5. Conversion of the MBR format to GPT happens only after you expand the datastore to a size larger than 2TB.
When you upgrade a VMFS3 datastore to VMFS5, the datastore uses the MBR format. Conversion to GPT happens only after you expand the datastore to a size larger than 2TB.
When you upgrade a VMFS3 datastore, remove from the storage device any partitions that ESXi does not recognize, for example, partitions that use the EXT2 or EXT3 formats. Otherwise, the host cannot format the device with GPT and the upgrade fails.
You cannot expand a VMFS3 datastore on devices that have the GPT partition format.