5 data transfer command components, Table 5-7 length fields, Table 5-8 data-phase command contents – Maxtor 10K V User Manual

Page 67

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Maxtor Atlas 10K V

5-9

5.5

DATA Transfer Command Components

Many of the SCSI commands cause data to be transferred between the initiator and
the drive. The content and characteristics of this data are command-dependent. Table
5-8 lists the informat
ion transmitted for all of the commands.

The “Length in CDB” column of Table 5-8 identifies the Command Descriptor
Block field used by the drive to determine how much command-related data are to
be transferred. The units (bytes or logical blocks) for the different Length fields are
implied by the Length Field Name as shown in Table 5-7:

Table 5-7

Length Fields

The DATA OUT column in Table 5-8 lists the information passed to the drive by the
initiator as part of the command. The DATA IN column lists the information sent to
the initiator by the drive.

Numbers in parentheses after an item indicate the item’s length in bytes. In some cases,
additional length information is communicated during the DATA phase. For example,
a FORMAT UNIT Defect List Header contains a Defect List Length field that
contains the total length of the Defect Descriptors that follow the Defect List Header.
Table 5-8 does not include these cases.

Table 5-8

DATA-Phase Command Contents

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 data sectors the initiator wants transferred or verified

Byte Transfer Length

Bytes of data the initiator wants transferred

Command

Length in CDB

Data Out (To Drive)

Data In (To Initiator)

CHANGE

DEFINITION

0

--

--

FORMAT UNIT

0

Defect List Header
Initialization Pattern (6-8)
Defect Descriptors

INQUIRY

Allocation

---

Standard Inquiry or a Vital Product
Data page

LOG SELECT

Parameter List

(must be 0)

--

--

LOG SENSE

Allocation

---

Log Page

MODE SELECT

Parameter List

Mode Parameter Header (4
Block Descriptor (8
Page(s))

--

MODE SENSE

Allocation

---

Block Descriptor (8)

PERSIST. RES. IN

PERSIST. RES.

OUT

READ (6) (10)

Transfer

---

Data

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