Quantum 10K II - Manual (Page 84)

SCSI Description
Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives 5–17
5.7 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 5-5 lists the information transmitted for all of the commands.
The “Length in CDB” column of Table 5-5 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 follows:
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 5-5 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 5-5 does not include these cases.