VMFS5 provides many improvements in scalability and performance.
VMFS5 has the following Characteristics:
Greater than 2TB storage devices for each VMFS5 extent.
Support of virtual machines with large capacity virtual disks, or disks greater than 2TB.
Increased resource limits such as file descriptors.
Standard 1MB file system block size with support of 2TB virtual disks.
Greater than 2TB disk size for RDMs.
Support of small files of 1KB.
Ability to open any file located on a VMFS5 datastore in a shared mode by a maximum of 32 hosts.
Scalability improvements on storage devices that support hardware acceleration. For information, see Storage Hardware Acceleration.
Default use of ATS-only locking mechanisms on storage devices that support ATS. For information about ATS-only locking and how to upgrade to ATS-only locking, see VMFS Locking Mechanisms.
Ability to reclaim physical storage space on thin provisioned storage devices. For information, see Array Thin Provisioning and VMFS Datastores.
Online upgrade process that upgrades existing datastores without disrupting hosts or virtual machines that are currently running. For information, see Upgrading VMFS Datastores.
For information about block size limitations of a VMFS datastore, see the VMware knowledge base article at http://kb.vmware.com/kb/1003565.