User Manual

SCSI Commands Reference Manual, Rev. J 108
www.seagate.com Direct Access Block commands (SPC-5 and SBC-4)
3.9 MODE SELECT(6) command
The MODE SELECT(6) command (see table 70) provides a means for the application client to specify medium, logical unit, or
peripheral device parameters to the device server. Device servers that implement the MODE SELECT(6) command shall also
implement the MODE SENSE(6) command. Application clients should issue MODE SENSE(6) prior to each MODE SELECT(6) to
determine supported mode pages, page lengths, and other parameters.
Logical units shall share mode parameter header and block descriptor values across all I_T nexuses. I_T nexus loss shall not affect
mode parameter header, block descriptor, and mode page values.
Logical units shall maintain current and saved values of each mode page based on any of the policies listed in table 71. The
mode page policy used for each mode page may be reported in the Mode Page Policy VPD page (see 5.4.14).
After a logical unit reset, each mode parameter header, block descriptor, and mode page shall revert to saved values if supported
or default values if saved values are not supported.
If an application client sends a MODE SELECT command that changes any parameters applying to other I_T nexuses, the device
server shall establish a unit attention (see SAM-5) condition for the initiator port associated with every I_T nexus except the I_T
nexus on which the MODE SELECT command was received, with the additional sense code set to MODE PARAMETERS CHANGED.
PF (Page Format) bit
0 A page format (PF) bit set to zero specifies that all parameters after the block descriptors are vendor specific.
1 A PF bit set to one specifies that the MODE SELECT parameters following the header and block descriptor(s) are structured as pages of
related parameters and are as defined in this manual. If the RTD bit is set to one then the PF bit is ignored.
RTD (revert to defaults) bit
0 An RTD bit set to zero specifies that the device server shall process the MODE SELECT command based on the other fields in the CDB and
parameter data.
1 An RTD_SUP bit (see SPC-5) set to one and an RTD bit set to one specifies that the device server shall revert:
a) current mode page values for all mode pages to their default values, if the SP bit is set to zero; and
b) current mode page values and saved mode page values for all pages to their default values, if the SP bit is set to one.
Table 70 MODE SELECT(6) command
Bit
Byte
7 6 5 4 3 2 1 0
0
OPERATION CODE (15h)
1
Reserved PF Reserved
RTD
SP
2
Reserved
3
4
PARAMETER LIST LENGTH
5
CONTROL
Table 71 Mode page policies
Mode page policy Number of mode page copies
Shared One copy of the mode page that is shared by all I_T nexuses.
Per target port A separate copy of the mode page for each target port with each copy shared by all initiator ports.
Per I_T nexus A separate copy of the mode page for each I_T nexus