VMware VMFS (Virtual Machine File System) is VMware, Inc.'s clustered file system used by the company's flagship server virtualization suite, vSphere.
It was developed to store virtual machine disk images, including snapshots.
Multiple servers can read/write the same filesystem simultaneously while individual virtual machine files are locked.
There are six (plus one for vSAN) versions of VMFS, corresponding with ESX/ESXi Server product releases.
A Java open source VMFS driver[9] enables read-only access to files and folders on partitions formatted with the Virtual Machine File System (VMFS) is developed and maintained by Fluid Operations.