VMware Virtual SAN is a new software-defined storage Tier that extends the vSphere Hypervisor to pool both compute and direct-attached storage. By clustering server direct-attached hard disk and solid state drives (HDDs and SSDs), Virtual SAN creates a distributed shared datastore designed and optimized for virtual machines. Virtual SAN is built in to the vSphere kernel and implements a distributed architecture that leverages SSDs for high-Performance read/write caching and HDDs for cost-effective data persistence. The technology is based on a highly available architecture with no single point of failure. It can withstand failures at the disk, server and network level with no data loss, thanks to built-in redundancy mechanisms that transparently store multiple copies of the data across disks and Hosts
