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Fibre Channel Interface Manual, Rev. D 187
12.9 Log Select command
The Log Select command provides a means for an initiator to manage statistical information about the drive
operation. This information is logged within the drive and can be sent to the initiator in response to a Log
Sense command from the initiator. The Log Select command format is shown in Table 120. The initiator sends
zero or more pages of control parameters in the Log Page format of Table 123. These log pages contain
parameters that command the drive to change selected threshold, or cumulative values of any or all drive logs.
The following tables in Section 12.9 apply for the Log Select command as indicators of functions that command
the drive to perform or enable for performance, control parameter bits the drive sets/resets/saves, log counts
that are kept, etc. For the Log Sense command, these tables apply as indicators of functions the drive reports
back to the host that it is enabled to perform, control parameter bits that are set/reset/saved, log counts that are
being kept, etc. Though the language of the descriptions is for the Log Select case, the application to the Log
Sense case should also be considered. Section 12.10 describes the Log Sense command, but the tables of
this section that apply are not repeated there.
The drives represented by this Interface Manual do not support keeping independent sets of log parameters
(one set for each initiator in the system). If at some point log parameters are changed (by a Log Select com-
mand) that affect initiators other than the initiator that sent the Log Select command, the drive generates a unit
attention condition for those other initiators, but not for the one that issued the Log Select command. When the
other initiators at a future time connect to the drive, the first command attempted would not execute and a
check condition status would be issued by the drive. A Request Sense command would normally follow and a
unit attention condition sense code be returned to these other initiators with an additional sense code of Log
Parameters Changed (one by one as they connect to the drive). See Section 12.13.1, Unit Attention page.
Field definitions (listed alphabetically)
Control
See Control Bytes in Section 11.2.1.6.
PC (Page Control)
This field defines the type of log parameter the initiator selects to change with the Log Select command.
00b Log current threshold values
01b Log current cumulative values
10b Log default threshold values
11b Log default cumulative values
Table 120: Log Select command (4Ch)
Bit
Byte
76543210
001001100
1000000PCRSP
Reserved
2 PC Reserved
3
Reserved
4
Reserved
5
Reserved
6
Reserved
7 (MSB)
Parameter List Length
8 (LSB)
9
Control
4Ch
Table
number
120
120