Maxtor 10K V manual Data Transfer Command Components, 8DATA-Phase Command Contents

5.5DATA 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 5-7Length 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 data sectors the initiator wants transferred or verified
Byte Transfer Length		Bytes of data the initiator wants transferred

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 5-8DATA-Phase Command Contents

Command	Length in CDB	Data Out (To Drive)	Data In (To Initiator)
CHANGE	0	--	--
DEFINITION
		Defect List Header
FORMAT UNIT	0	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
	Parameter List	Mode Parameter Header (4
MODE SELECT		Block Descriptor (8	--
		Page(s))
MODE SENSE	Allocation	---	Block Descriptor (8)
PERSIST. RES. IN
PERSIST. RES.
OUT
READ (6) (10)	Transfer	---	Data

Maxtor Atlas 10K V 5-9