Each Flexible Volume (FlexVol) is a separate WAFL file system, located on an aggregate and distributed across all disks in the aggregate.
Block device access with SUN protocols like iSCSI, FC, FCoE is done with LUN emulation similar to Loop device technique
on top of a FlexVol volume, thus each LUN on WAFL file system appears as a file,
yet have additional properties required for block devices