vSAN enables providers to protect consumer data, even in the event of disk, host, network, or rack failures, with built-in distributed RAID and cache mirroring. Resiliency is enhanced by defining availability on a per-VM basis. The number of host, network, disk, or rack failures to tolerate in a vSAN cluster can be customized based on customer, application, or business requirements.

vSAN supports clustering technologies from both Oracle and Microsoft. With Oracle Real Application Cluster (RAC), customers can run multiple Oracle RDBM instances, accessing the vSAN datastore to deliver better performance, scalability, and resilience. Additionally, Windows Server Failover Clustering (WSFC) can provide protection against application and service failures.

Technically, there is a minimum requirement of three ESXi hosts in a vSAN cluster. Although VMware fully supports three-node configurations, there are limitations when compared with configurations of four or more nodes. In particular, in the event of a failure, there is no way for vSAN to rebuild the components on another host in the cluster to tolerate another failure. There is also an operational limitation because vSAN will not have the ability to migrate all data from a node during maintenance.

Business continuity and disaster recovery are paramount for ensuring that consumers’ business critical environment, data, and online presence are available with minimal downtime. vSAN recoverability can be addressed through a range of solutions, from near-line capabilities such as snapshots, offline capabilities provided by vSphere storage integrated backup solutions (using APIs for data protection), or inter-data center solutions, such as stretched cluster.