A physical disk or disk LUN is always exported as a full disk. In that case, virtual disk drivers (vds and vdc) forward I/O from the virtual disk and act as a pass-through to the physical disk or disk LUN.
A physical disk or disk LUN is exported from a service domain by exporting the device that corresponds to the slice 2 (s2) of that disk without setting the slice option. If you export the slice 2 of a disk with the slice option, only this slice is exported and not the entire disk.