User Manual

SCSI Commands Reference Manual, Rev. J 106
www.seagate.com Direct Access Block commands (SPC-5 and SBC-4)
3.8 LOG SENSE command
The LOG SENSE command (see table 69) provides a means for the application client to retrieve statistical or other operational
information maintained by the SCSI target device about the SCSI target device or its logical units. It is a complementary
command to the LOG SELECT command. See clause 4.2 of this manual for more information on returned log pages.
SP (Saving Parameters) bit
1 If saving log parameters is implemented, an SP bit set to one specifies that the device server shall perform the specified LOG SENSE com-
mand and shall save all log parameters identified as saveable by the DS bit to a nonvolatile, vendor specific location. Saving parameters
is an optional function of the LOG SENSE command. If the logical unit does not implement saving log parameters and if the save param-
eters (SP) bit is set to one, then the command shall be terminated with CHECK CONDITION status, with the sense key set to ILLEGAL
REQUEST, and the additional sense code set to INVALID FIELD IN CDB.
0 An SP bit set to zero specifies the device server shall perform the specified LOG SENSE command and shall not save any log parameters.
For data counter log parameters (i.e., when the FORMAT AND LINKING field in the parameter control byte in the log parameter
structure (see 5.2.2.2) contains 00b or 10b), the page control (PC) table 66 specifies which log parameter values are to be
returned by a device server in response to a LOG SENSE command.
For list parameters (i.e., when the FORMAT ANDLINKING field in the parameter control byte in the log parameter structure (see
5.2.2.2) contains 01b or 11b), the PC field shall be ignored. If the parameters specified by the PAGE CODE field and SUBPAGE
CODE field in the CDB are list parameters, then the parameter values returned by a device server in response to a LOG SENSE
command are determined as follows:
1) the current list parameter values, if there has been an update to a list parameter value (e.g., by a LOG SELECT command or by a device
specific event) in the specified page or pages since the last logical unit reset occurred;
2) the saved list parameter values, if saved parameters are implemented and an update has not occurred since the last logical unit reset; or
3) the vendor specific default list parameter values, if saved values are not available or not implemented and an update has not occurred
since the last logical unit reset.
Table 69 LOG SENSE command
Bit
Byte
7 6 5 4 3 2 1 0
0 OPERATION CODE (4Dh)
1 Reserved Obsolete SP
2 PC PAGE CODE
3 SUBPAGE CODE
4 Reserved
5 (MSB)
PARAMETER POINTER
6 (LSB)
7 (MSB)
ALLOCATION LENGTH
8 (LSB)
9 CONTROL