User Manual

SCSI Commands Reference Manual, Rev. J 305
www.seagate.com Parameters for direct access devices
5.2.2.2 Log parameter format
5.2.2.2.1 Introduction
Most log pages contain one or more special data structures called log parameters (see table 267). Log parameters may be data
counters of a particular event(s), the conditions under which certain operations were performed, or list parameters that contain
a character string description of a particular event.
Each log parameter begins with a four-byte parameter header followed by one or more bytes of PARAMETER VALUE data.
PARAMETER CODE field
The PARAMETER CODE field identifies the log parameter being transferred for that log page. The device server shall return the log parameters
in a log page in ascending order based on the value in their PARAMETER CODE field.
If an application client specifies a value in the PARAMETER CODE field in the LOG SELECT command parameter data that is reserved or not
implemented by the logical unit, then the device server shall terminate the command with CHECK CONDITION status, with the sense key set to
ILLEGAL REQUEST, and the additional sense code set to INVALID FIELD IN PARAMETER LIST.
PARAMETER LENGTH field
The PARAMETER LENGH field specifies the length in bytes of the PARAMETER VALUE field that follows. If the application client specifies a
parameter length that results in the truncation of the PARAMETER VALUE field, the command shall be terminated with CHECK CONDITION sta-
tus, with the sense key set to ILLEGAL REQUEST, and the additional sense code set to INVALID FIELD IN PARAMETER LIST.
If an application client sends a log parameter that is not supported by the logical unit, the command shall be terminated with CHECK CONDI-
TION status, with the sense key set to ILLEGAL REQUEST, and the additional sense code set to INVALID FIELD IN PARAMETER LIST.
PARAMETER VALUE field
If the application client sends a log parameter value of the PARAMETER VALUE field that is outside the range supported by the logical unit, and
rounding is implemented for that parameter, the device server may either:
a) round to an acceptable value and terminate the command as described in 2.3; or
b) terminate the command with CHECK CONDITION status, with the sense key set to ILLEGAL REQUEST, and the additional sense code set
to INVALID FIELD IN PARAMETER LIST.
If the parameter data for one LOG SELECT command contains more than one log page and the log pages are not in ascending order by page
code value then subpage code value, then the device server shall terminate the command with CHECK CONDITION status, with the sense key
set to ILLEGAL REQUEST, and the additional sense code set to INVALID FIELD IN PARAMETER LIST.
If the parameter data for one LOG SELECT command contains more than one log parameter in any one log page and the log parameters are not
in ascending order by parameter code value, then the device server shall terminate the command with CHECK CONDITION status, with the
sense key set to ILLEGAL REQUEST, and the additional sense code set to INVALID FIELD IN PARAMETER LIST.
Application clients should send LOG SENSE commands prior to sending LOG SELECT commands to determine supported log pages and page
lengths.
The SCSI target device may provide independent sets of log parameters for each logical unit or for each combination of logical units and I_T
nexuses. If the SCSI target device does not support independent sets of log parameters and any log parameters are changed that affect other
I_T nexuses, then the device server shall establish a unit attention condition (see SAM-5) for the initiator port associated with every I_T nexus
except the I_T nexus on which the LOG SELECT command was received, with the additional sense code set to LOG PARAMETERS CHANGED.
Table 267 Log parameter
Bit
Byte
7 6 5 4 3 2 1 0
0 (MSB)
PARAMETER CODE
1 (LSB)
2 PARAMETER CONTROL BYTE – (see 5.2.2.2.2)
3 PARAMETER LENGTH (N-3)
4
PARAMETER VALUE. . .
n