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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 information 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