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LOG SENSE 6.Command Specification
SONY AIT-5 drive SDX-1100V series Ver.1.0 6-13
6.6. LOG SENSE 4Dh
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation Code (4Dh)
1 Reserved PPC (0) SP (0)
2 PC Page Code
3 (MSB)
4
Reserved
5
6
Parameter Pointer
(LSB)
7 (MSB)
8
Allocation Length
(LSB)
9 Control
The LOG SENSE command provides a means for the initiator to retrieve statistical information maintained by the
device about its own hardware or the installed media. It is a complementary command to the LOG SELECT
command.
SP: The device does not have non-volatile RAM into which it may save parameters. Therefore, the Save Page bit
is not supported by this device and will always be set to ZERO. If the SP bit is set, the command will be terminated
with a CHECK CONDITION status with the sense key set to ILLEGAL REQUEST, and an ASC of INVALID FIELD
IN CDB.
PPC: The Parameter Pointer Control bit will always be set to ZERO. This indicates that the parameter data
requested from the device will start with the parameter code specified in the Parameter Pointer field and return the
number of bytes specified in the Allocation Length field in ascending order of parameter codes from the specified
log page. A PPC bit of ZERO and a Parameter Pointer field of ZERO cause all available parameter data for that
page code to be returned to the initiator. If the PPC bit is set or the Parameter Pointer is larger than the highest
numbered parameter on the page, then the target will terminate the command with CHECK CONDITION status.
The sense key will be set to ILLEGAL REQUEST and the ASC will be set to INVALID FIELD IN CDB. If the drive
does not support a parameter code within this page then it will not return any data associated with this parameter.
PC: The Page Control field defines the type of parameter values to be selected. The page control field is defined
below:
Table 6-8: Page Control field values
Value Type of Parameter Values
00b
01b
10b
11b
Current Threshold Values
Current Cumulative Values
Default Threshold Values
Default Cumulative Values
The Current Threshold Values and the Default Threshold Values are non-changeable and the both will return the
same values-i.e. the maximum values that each parameter can attain. Note that for some parameters the term
threshold value has no meaning. See the description of individual pages/ parameters below for more details.
The Current Cumulative Values are the values computed since the last reset of the device (either by
power-cycling, BUS DEVICE RESET or SCSI RESET). Note that for some parameters these values cannot be
reset by any method. See description of individual pages/parameters below for more details.
The Default Cumulative Values are the values to which each parameter gets initialized on a reset condition as
described above. See description of individual pages/parameters below for more details.