VMware VMFS VMware VMFS (Virtual Machine File System) is VMware, Inc.’s cluster file system designed for VMware Infrastructure or VMware vSphere. Basically VMFS used to store virtual machine disk images, including snapshots.

According to Wikipedia,

  • VMFS version 1 was used by ESX Server v1.x, which is no longer sold. It didn’t feature the cluster filesystem properties and was used only by a single server at a time. VMFS1 is a flat filesystem with no directory structure. — Officially named “VMware File System”
  • VMFS version 2 is used by ESX Server v2.x and (in a limited capacity) v3.x. VMFS2 is a flat filesystem with no directory structure. — Officially named “VMware File System”
  • VMFS version 3 is used by ESX Server v3.x and vSphere (4.x). As a most noticeable feature, it introduced directory structure in the filesystem. Older versions of ESX Server cannot read or write VMFS3 volumes. Beginning from ESX 3 and VMFS3, virtual machine configuration files are stored in the VMFS partition by default. — Officially named “VMware Virtual Machine File System”

In order to know the exact VMFS version number, see below:

  1. VMware ESX 3 – VMFS ver 3.21
  2. VMware ESX 3.5 – VMFS ver 3.31
  3. VMware vSphere 4 – VMFS ver 3.33
  4. VMware vSphere 4.1 – VMFS ver 3.46

Please take note that migration between different VMFS version may cause some problem in the sense of vSphere vStorage features, probably you may read more here or refer to vSphere Upgrade Guide.