If your datastores were formatted with VMFS2 or VMFS3, you must upgrade the datastores to VMFS5.

When you perform datastore upgrades, consider the following items:

To upgrade a VMFS2 datastore, you use a two-step process that involves upgrading VMFS2 to VMFS3 first. To access the VMFS2 datastore and perform the VMFS2 to VMFS3 conversion, use an ESX/ESXi 4.x or earlier host.

After you upgrade your VMFS2 datastore to VMFS3, the datastore becomes available on the ESXi 6.0 host, where you complete the process of upgrading to VMFS5.

You can perform a VMFS3 to VMFS5 upgrade while the datastore is in use with virtual machines powered on.

While performing an upgrade, your host preserves all files on the datastore.

The datastore upgrade is a one-way process. After upgrading your datastore, you cannot revert it back to its previous VMFS format.

An upgraded VMFS5 datastore differs from a newly formatted VMFS5.

Comparing Upgraded and Newly Formatted VMFS5 Datastores

Characteristics

Upgraded VMFS5

Formatted VMFS5

File block size

1, 2, 4, and 8MB

1MB

Subblock size

64KB

8KB

Partition format

MBR. Conversion to GPT happens only after you expand the datastore to a size larger than 2TB.

GPT

Datastore limits

Retains limits of VMFS3 datastore.

VMFS locking mechanism

ATS+SCSI

ATS-only (on hardware that supports ATS)

ATS+SCSI (on hardware that does not support ATS)

For more information about VMFS locking mechanisms and how to upgrade to ATS-only, see the vSphere Storage publication.