As a cluster file system, VMFS lets multiple ESXi hosts access the same VMFS datastore concurrently.

Figure 1. Sharing a VMFS Datastore Across Hosts
The image shows a single VMFS datastore being accessed by multiple servers.

For information on the maximum number of hosts that can connect to a single VMFS datastore, see the Configuration Maximums document.

To ensure that the same virtual machine is not accessed by multiple servers at the same time, VMFS provides on-disk locking.

Sharing the same VMFS volume across multiple hosts offers the following advantages:

  • You can use VMware Distributed Resource Scheduling (DRS) and VMware High Availability (HA).

    You can distribute virtual machines across different physical servers. That means you run a mix of virtual machines on each server so that not all experience high demand in the same area at the same time. If a server fails, you can restart virtual machines on another physical server. In case of a failure, the on-disk lock for each virtual machine is released. For more information about VMware DRS, see the vSphere Resource Management documentation. For information about VMware HA, see the vSphere Availability documentation.

  • You can use vMotion to migrate running virtual machines from one physical server to another. For information about migrating virtual machines, see the vCenter Server and Host Management documentation.