vSphere 5 and its near predecessors are inherently highly scalable clustered environments. From the very beginning of the life of ESX, VMware Virtual Machine File System (VMFS) has been the core element that holds the environment together.
VMFS is the core component of vSphere’s storage virtualization as it abstracts the underlying storage and presents it to Virtual Machines (VMs) in various formats: virtual disks, PassthruRDMs, nonPassthruRDMs, snapshots, and so on. More on that later!
VMFS evolved from a flat file system to a highly specialized clustered file system over four generations.
The first version of VMFS, which shipped with ESX 1.x, was a flat file system (did not provide directories) ...