Log Sense (4D) - IBM DDRS-39130 - Ultrastar 9.1 GB Hard Drive Specifications

7.8 LOG SENSE (4D)

Byte
7 6
0
1 LUN
2 PC
3
4
5 (MSB)
6
7 (MSB)
8
9
Figure 66. L O G SENSE (4D)
The LOG SENSE command allows the initiator to retrieve the statistical data about the drive.
PPC (Parameter Pointer Control) bit must be set to zero. This specifies that the drive start transferring
data starting from the field specified in the parameter pointer field for the number of bytes specified by
the allocation length. If the PPC bit is set to 1, CHECK CONDITION status is returned with a Sense
Key of Illegal Request and additional sense code of Invalid Field in CDB.
SP (Save Parameters) bit set to 0 specifies that the drive does not save any log parameters. If set to 1 all
page parameters that are savable (those pages denoted by a DS = 0 in the parameter header control
byte) are saved.
PC (Page Control) field defines the type of parameters to be selected. This field must be set to 01b to
specify the current cumulative values or 11b to specify the default cumulative values.
As the file does not support the threshold pages any other value in this field will cause the command to
end with a CHECK CONDITION with a sense key of illegal request and an additional sense code of
invalid field in CDB.
Page Code field identifies which page is being requested. This field must be set to the values indicated in
Page 0. If the Page Code value is invalid a CHECK CONDITION status is returned with a Sense Key
of Illegal Request and additional sense code of Invalid Field in CDB.
Parameter Pointer Field specifies the beginning field for the transfer. This field must be set to 0000h. If
the Parameter Pointer Field is not zero a CHECK CONDITION status is returned with a Sense Key of
Illegal Request and additional sense code of Invalid Field in CDB.
Allocation Length field specifies the maximum number of bytes the Initiator has allocated for returned
Log Sense Data. No bytes are transferred if the length is zero. This condition is not considered an error.
The target terminates the Data In phase when all available Log Sense data has been transferred or when
the number of bytes equals the allocation length, whichever is less.
Bit
5 4 3
Command Code = 4Dh
Reserved = 0
Page Code
Reserved = 0
Parameter Pointer = 0
Allocation Length
Reserved = 0
2 1 0
PPC = 0 SP
(LSB)
(LSB)
FLAG LINK
SCSI C O M M A N D SET
77