XenServer supports both local storage in the form of SATA, SAS, and SSD. It also supports networked storage in the form of SAN and NAS. XenServer uses NFSv3 over TCP for remote file storage on NAS and iSCSI and Fibre Channel for block storage on SAN. Through XenCenter, which uses the XenAPI (xapi), XenServer provides an abstraction layer for physical storage resources to be addressed, managed, and optimized in a virtual environment.
Storage is organized as storage repositories in XenServer; these contain virtual disk images, physical block devices, and virtual block devices. In XenServer, a storage respository is an abstraction of the physical disk device, which can be either locally attached or on a SAN. Virtual disk images are created as a storage abstraction that can be presented to virtual machines for storage. The virtual machine sees this as a virtual disk. A XenServer storage respository...