Seagate Fibre Channel Interface - Manual (Page 206)

192 Fibre Channel Interface Manual, Rev. D
Field definitions (listed alphabetically)
Log Parameter
Each Log Parameter structure begins with a four-byte parameter header followed by one or more bytes of parameter value
data. Log Parameter structures are in the format given in Table 124.
Log Parameter Structures
Most log pages contain one or more special data structures called Log Parameters. Log Parameters may be data counters
that record a count of a particular event (or events) or list parameters (strings) that contain a description of a particular
event. List parameters are not currently supported by the drives represented by this manual.
Page Code
Valid page codes are listed in Table 126.
Page Length
The total number of bytes of Log Parameter structures that follow these first four control block bytes. If the initiator sends a
page length that results in the truncation of any parameter, the target terminates the command with Check Condition status.
The sense key is set to Illegal Request with the additional sense code set to Invalid Field In Parameter List.
Field definitions (listed alphabetically)
DS (Disable Save)
0 The drive supports Log Select and Log Sense data saving for that log parameter. The drive saves the current cumu-
lative and the current threshold parameter values in response to a Log Select or Log Sense command with a SP bit
of one.
1 The drive does not support saving that log parameter in response to a Log Select or Log Sense command with a SP
bit of one.
DU (Disable Update)
0 The drive updates the log parameter value to reflect all events that should be logged by that parameter.
1 The drive does not update the log parameter value except in response to a Log Select command that specifies a
new value for the parameter.
For the Log Select command, this applies only to the cumulative log parameter values (indicated by 01 in the PC field of the
Log Select and Log Sense command descriptor block).
The DU flag is set to one when the current cumulative value of the parameter counter it controls reaches its maximum value
(see Parameter Length definition for this table). Upon reaching this maximum value, the data counter does not wrap around
and start over at zero. Incrementing of other counters within the same log pages ceases. Counters do not restart automati-
cally if the overflowed counter is re-initialized. If the data counter reaches its maximum value during the execution of a com-
mand, the drive completes the command. Drive counter updates are performed in the background. This means a counter
may overflow long after a command has completed, so the drive must treat this condition as a Unit Attention with the addi-
tional sense code set to Log Counter at max for all initiators if RLEC=1 (Report Log exception condition bit of the Control
Mode Page 0Ah).
Table 124: Log Parameter structure
Bit
Byte
7 6 5 4 3 2 1 0
0 (MSB) Parameter Code
1 (LSB)
2 DU DS TSD ETC TMC LBIN LP
3
Parameter Length (n–3 bytes)
4
:
n
Parameter Value
Table
number
123
123
123
123
Table
number
124
124