Operating instructions

SEPTEMBER 2005 PRELIMINARY MAGNUM 1X7 LTO AUTOLOADER
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OVERVIEW OF THE
AUTOLOADER AS A SCSI DEVICE
This chapter provides background information for understanding how the
Magnum 1x7 LTO Autoloader operates as a device on a SCSI bus. It provides
an overview of the following:
 The autoloader’s relationship to the SCSI bus
 The elements and element addresses of the autoloader
 SCSI bus communication, including bus phases, messages, commands, and
statuses
2.1 RELATIONSHIP TO THE SCSI BUS
The Small Computer System Interface (SCSI) is a standard that enables a host
computer and peripheral equipment, such as the autoloader and its tape drive,
to communicate. The autoloader and the tape drive each include independent
SCSI controllers.
The physical components of the SCSI system consist of the following:
 Initiator. A computer equipped with a SCSI bus adapter card which allows
it to send commands, messages, and data across the SCSI bus to targets such
as the autoloader or its internal tape drive. The initiator can also receive
data, messages, and status from the targets.
 Ta r g e t s . Devices capable of receiving commands from an initiator. The
autoloader and its internal tape drive are independent targets. The
autoloader is the target for cartridge inventory and movement operations.
The tape drive is the target for read and write operations.
 SCSI bus. The SCSI cables that connect the SCSI bus adapter card to the
autoloader, tape drive, and other devices form the SCSI bus and provide a
pathway for passing information between the initiator and the targets. The
autoloader uses a wide, low-voltage differential (LVD) SCSI configuration.
The SCSI bus attached to the autoloader must be terminated at both ends.