A system administrator wants to add five external juke boxes with four disks each to the wide SCSI controller of a server. The internal boot disks and CD-ROM are installed on a second controller. How

4 would represent only the disks in a single jukebox, ignoring the remaining four enclosures connected to the controller.

5 would represent only the number of jukebox enclosures, not the individual disk LUNs each enclosure exposes to the host.

In SCSI architecture, a jukebox (multi-disk enclosure) connects as a single SCSI target ID on the bus and exposes each internal disk as a distinct Logical Unit Number (LUN). With 5 jukeboxes each containing 4 disks, the server sees 5 x 4 = 20 LUNs. The internal boot disks and CD-ROM on the second controller are irrelevant to this count because they reside on a separate SCSI bus.

25 incorrectly adds the 5 jukebox units themselves to the 20 disk LUNs; in SCSI, the enclosure is the SCSI target and its disks are the LUNs - the enclosure does not appear as a separate addressable LUN alongside its disks.