If you have a ACSI device that supports more than one LUN (Logical
Unit Number), e.g. a CD jukebox, you should say Y here so that all
will be found by the ACSI driver. An ACSI device with multiple LUNs
acts logically like multiple ACSI devices. The vast majority of ACSI
devices have only one LUN, and so most people can say N here and
should in fact do so, because it is safer.