User's Guide

Quantum Scalar Intelligent Libraries SCSI Reference Guide Guide 1
SCSI Command Support
Device Model
Quantum intelligent libraries support both a Media Changer (device type 08h) and, depending on the library
model and configuration, a Controller Device (device type 0Ch). The Controller Device is used primarily to
aid initialization and discovery for the servers in conjunction with the library’s Logical Library model. In the
case of a Scalar i40 and Scalar i80, which do not support data Appliance (DA) blades, or Scalar i500 and
Scalar i6000 libraries without Data Appliance (DA) blades, there is no Controller Device. In such
configurations, tape drives host the library control path to the logical library partitions and hereby provide
access to the Media Changers.
This device model approach works by having the Controller Device (typically at LUN 0) respond to
commands directed at LUN 0, including the REPORT LUNS command, and the Media Changer(s) (one
Media Changer per logical library partition) respond to commands on LUN1. This approach allows an
initiator (host) to issue a REPORT LUNS command to the Controller Device to retrieve a listing of all
available logical units, to determine the presence of connected data transfer device(s) and Media
Changer(s). For systems with Fibre Channel (FC) ports, this is an advantage as there are large number of
possible logical units to search. (In the case of a Scalar i40, and Scalar i80, or Scalar i500 and Scalar i6000
without DA Blades, this command should be issued to the tape drives.)
Note that the DA Blade Controller Device is not a pure Controller Device, in that it does not support all the
mandatory commands defined by SCC, but this is an accepted industry practice established by vendors of
bridges and routers.
Additional commands and parameters supported by the DA Blade Controller LUN (such as Maintenance In)
are for use by Quantum’s Host Registration Services software, and are not included in this manual.
Note
“DA Blade” is a generic term used in this manual to describe an
FC-to-FC I/O blade.