Quantum 1200 Series DAT Autochanger Uživatelská příručka stáhnout pdf (Strana 29)

81-81200-02 REV A01 January 2005 3-1

CHAPTER 3

SCSI Messages

This chapter provides a detailed description of the SCSI messages SDLT tape drives support.

Specifically, it covers the following topics:

• “Message Format” lists the specific format of SCSI messages.

• “Supported SCSI Messages” contains descriptions of each of the messages supported by the drive.

3.1 Message Format

A message can be one or more bytes in length. One or more messages can be sent during a single

MESSAGE phase, but a message cannot be split across multiple MESSAGE phases. The initiator is

required to end the MESSAGE OUT phase (by negating ATN) when it sends certain messages that are

identified in Table 3-3.

When a connection to the SDLT tape drive is established (that is, the drive is selected with ATN

asserted), the first message byte passed by the initiator must be either an IDENTIFY, ABORT TASK

SET, or TARGET RESET message. If not, the drive discards the message, saves no status information,

and enters the BUS FREE phase.

If an initiator supplies an unsupported message (for example, TASK COMPLETE or a reserved or

undefined message code), the drive returns a MESSAGE REJECT message and continues where it left

off (possibly returning to MESSAGE OUT if ATN is raised).

SDLT 600

SCSI Interface Guide

SCSI Messages

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Quantum 1200 Series DAT Autochanger Uživatelská příručka Strana 29