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 multiple hosts do not access the same virtual machine at the same time, VMFS provides on-disk locking.

Sharing the VMFS volume across multiple hosts offers several advantages, for example, the following:

  • 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. If the failure occurs, 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.

To create a shared datastore, mount the datastore on those ESXi hosts that require the datastore access.