Linux in a Nutshell, 6th Edition

Shared Disks

To run multiple ESX servers, you need a shared data store. It can be SAN-based block storage (e.g., Fibre Channel or iSCSI) or a NAS connection (NFS), but you need some place the servers can all access the same data. For block storage, VMware uses a shared filesystem, vmfs, which is designed to handle multiple systems reading and writing to the same drive.