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SCSI Commands Reference Manual, Rev. J 111
www.seagate.com Direct Access Block commands (SPC-5 and SBC-4)
3.11 MODE SENSE(6) command
3.11.1 MODE SENSE(6) command introduction
The MODE SENSE(6) command (see table 73) provides a means for a device server to report parameters to an application client.
It is a complementary command to the MODE SELECT(6) command. Device servers that implement the MODE SENSE(6)
command shall also implement the MODE SELECT(6) command.
DBD (disable block descriptors) bit
0 A disable block descriptors (DBD) bit set to zero specifies that the device server may return zero or more block descriptors in the
returned MODE SENSE data.
1 A DBD bit set to one specifies that the device server shall not return any block descriptors in the returned MODE SENSE data.
PC (Page Control) field
The page control (PC) field specifies the type of mode parameter values to be returned in the mode pages. The PC field is defined in table 74.
The PC field only affects the mode parameters within the mode pages, however the PS bit, SPF bit, PAGE CODE field, SUBPAGE CODE field, and
PAGE LENGTH field should return current values (i.e., as if PC is set to 00b). The mode parameter header and mode parameter block descriptor
should return current values.
Some SCSI target devices may not distinguish between current and saved mode parameters and report identical values in response to a PC
field of either 00b or 11b. See also the description of the save pages (SP) bit in the MODE SELECT command.
PAGE CODE and SUBPAGE CODE fields
The PAGE CODE and SUBPAGE CODE fields specify which mode pages and subpages to return (see table 349).
ALLOCATION LENGTH field
The ALLOCATION LENGTH field is defined in 2.2.6.
Table 73 MODE SENSE(6) command
Bit
Byte
7 6 5 4 3 2 1 0
0
OPERATION CODE (1Ah)
1
Reserved DBD Reserved
2
PC PAGE CODE
3
SUBPAGE CODE
4
ALLOCATION LENGTH
5
CONTROL
Table 74 Page control (PC) field
Code Type of parameter Reference
00b
Current values 3.11.1.1
01b
Changeable values 3.11.1.2
10b
Default values 3.11.1.3
11b
Saved values 3.11.1.4