VMware vSAN™ aggregates local or direct-attached data storage devices to create a single storage pool shared across all hosts in the vSAN cluster. vSAN eliminates the need for external shared storage, and simplifies storage configuration and virtual machine provisioning.
vSAN is a distributed layer of software included in the ESXi hypervisor, and it is fully integrated with VMware vSphere. vSAN supports vSphere features that require shared storage, such as High Availability (HA), vMotion, and Distributed Resource Scheduler (DRS). VM storage policies enable you to define virtual machine storage requirements and capabilities.
Each host in a vSAN cluster can contribute storage to the cluster. These storage devices combine to create a single vSAN datastore. A hybrid vSAN cluster uses flash devices for the cache tier and magnetic drives for the capacity tier. An all-flash vSAN cluster uses flash devices for both the cache tier and the capacity tier. This architecture creates a flash-optimized, resilient shared datastore designed for virtual environments.