Quantum 10K II - Manual (Page 126)

SCSI Description
Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives 5–59
5.14 MODE SELECT (6) Command (15h)
SCSI refers to the drive’s operational parameters as its mode parameters. SCSI
groups the mode parameters by function into a set of data structures referred to as
mode pages. The MODE SELECT (6) command allows the initiator to modify some
of these mode pages and thereby control some of the drive’s operational
characteristics. The Save Page (SP) option in the Command Descriptor Block makes
the changes permanent. The new mode parameters are then stored in the drive’s
non-volatile memory.
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation Code (15h)
1 Reserved PF Reserved SP
2 – 3 Reserved
4 Parameter Length List
5 Control
Figure 5–24 MODE SELECT (6) Command Descriptor Block — Data Format
Table 5–25 MODE SELECT (6) Command — Field Descriptions
Data Field Description
PF Page Format. The drive ignores the content of this field and produces a
mode parameter list that contains a mode header optionally followed by
a sector descriptor and one or more pages that conform to the format
shown here.
SP Save Pages. When SP = 0, the drive performs the specified MODE SELECT
operation and does not save any pages. When SP = 1, the drive performs
the specified operation and stores all savable pages, (PS =1 on MODE
SENSE return) including any sent during the data-out buffer transfer. The
changes made when SP = 1 become permanent changes to the drive’s
SCSI setup.
Parameter List Length This field tells the drive how many bytes of Mode Parameters to fetch in
the data-out buffer transfer. A CHECK CONDITION status is returned if this
value truncates a page.