Where I live, a graduate with an MBBS degree (Master of Medicine, Master of Surgery) is called a doctor. To me, strictly speaking, he is a doctor only...
In computer networking, a virtual storage area network (VSAN) is a collection of ports from a set of connected Fibre Channel switches, that form a virtual fabric. Ports within a single switch can be partitioned into multiple VSANs, despite sharing hardware resources.
VMware VSAN (VMware Virtual SAN) is a storage feature integrated in the vSphere 5.5 kernel that pools disk space from multiple ESXi hosts. Download: Exclusive guide to VMware vSphere basics.