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LOG SENSE 6.Command Specification
SONY AIT-3Ex drive SDX-800V series Ver.1.1 6-13
6.6. LOG SENSE 4Dh
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation Code (4Dh)
1 Obsolete 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
LOG SENSE provides a means for the Host 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 shall always be set to ZERO. If the SP bit is set, the command will be terminated
with CHECK CONDITION status with the sense key set to ILLEGAL REQUEST, and an additional sense code of
INVALID FIELD IN CDB.
PPC: The Parameter Pointer Control bit shall 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 shall terminate the command with CHECK CONDITION status. The sense
key shall be set to ILLEGAL REQUEST and the additional sense code shall be set to INVALID FIELD IN CDB. If the
drive does not support a parameter code within this page then it shall 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 will both 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.