Quantum 1200 Series DAT Autochanger Podręcznik Użytkownika Pobierz pdf (Strona 46)

Overview of SCSI Command and Status Processing SDLT 600 SCSI Interface Guide

4-4 January 2005 81-81200-02 REV A01

4.1.2 DATA Phase Command Components

Many of the SCSI commands cause data to be transferred between the initiator and the SDLT tape

drive. The content and characteristics of this data are command-dependent. Table 4-4 lists the

information transmitted with each of the commands.

The drive uses the “Length in CDB” column of Table 4-4 to determine how much command-related

data are to be transferred. Table 4-3 lists how the units (bytes or logical blocks) for the different Length

fields are implied by the Length field name as follows:

The Data Out column in Table 4-4 lists the information the initiator passes to the drive as part of the

command. The Data In column lists the information the drive sends to the initiator. Numbers in

Table 4-2. Status Codes

Status

Code

Definition Meaning

00h GOOD The drive successfully completed the command.

02h CHECK

CONDITION

An exception condition occurred and the drive has established

a Contingent Allegiance condition.

08h BUSY The drive cannot currently service the command and has

discarded the CDB. The initiator may retry the command later.

18h RESERVATION

CONFLICT

The drive returns this status when an initiator attempts to

reserve the drive when another initiator has already reserved it

with a RESERVE UNIT, RESERVE (10), or PERSISTENT

RESERVE OUT command. The drive never returns this status

for INQUIRY or REQUEST SENSE commands.

Table 4-3. Units for Length Fields

Field Name Units Implied

Allocation Length Bytes of data the drive is allowed to send to the initiator.

Parameter List Length Bytes of data the initiator has available for the drive.

Transfer Length Logical number of data blocks or data bytes the initiator wants

transferred or verified.

Byte Transfer Length Bytes of data the initiator wants transferred.

1 2 ... 41 42 43 44 45 46 47 48 49 50 51 ... 293 294

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Quantum 1200 Series DAT Autochanger Podręcznik Użytkownika Strona 46