Compaq Infortrend manual Creating LUN Masks, 2 Host-LUN Mapping, 3 LUN Mask

Figure 8 - 2 Host-LUN Mapping

Creating LUN Masks

User can configure the storage subsystem to appear as 32 LUNs per Fibre target ID. Each LUN can be mapped with a storage unit -a partition or the entire logical drive. The configuration of logical units depends on host applications and how many drives and drive channels have been employed in the storage system.

The diagram below shows the idea of the virtual connection and the physical connection from host computers to drives. There can be many host computers connected across a storage network and a system administrator may want to make each storage unit available for certain host systems while forbidden for some others.

Figure 8 - 3 LUN Mask

	The access control can also be implemented by filter drivers.
	However, comparing to the control by software, access control based
	on controller LUN mapping can avoid overheads on server and the
	additional I/O latency.
	The LUN map combines Host ID (in the Fibre case, a 64-bit "port
	name;" in the SCSI case, the initiator ID) with the list of attributes of
	a LUN map that originally only consisted of the channel, target ID,
	and the LUN number.
Fibre Operation	8-15