Quantum 10K II - Manual (Page 128)

SCSI Description
Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives 5–61
MODE SELECT (6) Command (15h) (continued)
5.14.2 Mode Page Types
The drive maintains three distinct sets of mode pages. They are the current page, the
default page, and the saved page. The drive also reports a fourth set of changeable
pages. The page types are defined in Table 5-27.
Table 5–27 Mode Page Types
Page Type Definition
Current The current mode page set applies to all initiators and defines the drive’s mode. The
SCSI-2 specification states that a drive can maintain Mode parameters on a per-
initiator basis if it so chooses. The Drives do not support this option.
The current mode page set contains the values supplied in the last MODE SELECT
command received from an initiator. If no initiator has sent a MODE SELECT
command since the drive was last reset or powered up, the current pages contain
• Saved values if saved pages exist (from a previous MODE SELECT command SP
parameter).
• Default values if pages have never been saved.
The drives generate a Unit Attention condition for all initiators (except for the one
that was the source of the MODE SELECT command) whenever one initiator
modifies the Mode parameters.
Default The default mode page set contains the factory default values that are listed in each
page’s description.
Saved The saved mode page set contains values preserved in the drive’s non-volatile
memory by a previous SP-modified MODE SELECT command.
Changeable The changeable mode page set provides a means for an initiator to determine which
pages it is allowed to change and the specific bits within those pages that it is
allowed to change. This page set is read-only and is fetched with a MODE SENSE
command.
5.14.3 Mode Parameter List
Figure 5-25 shows the format of the Mode Parameter List that is passed by the
initiator to the drive during the command’s data-out buffer transfer. Table 5-28
describes the fields. Figure 5-26 and Table 5-29 provides a description of the data
format and fields of the Mode Parameter Header.
Bit
Byte
7 6 5 4 3 2 1 0
0 – 3 Mode Parameter Header
4 – 11 Block Descriptor
(optional)
4 – n
or
12 – n
Page(s)
(optional)
Figure 5–25 Mode Parameter List — Data Format