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SCSI Interface Product Manual, Rev. B
8.8
LOG SELECT command (4Ch)
The LOG SELECT command provides a means for an application client to manage statistical information main-
tained by the device about the device or its logical units. 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 for-
mat is shown in Table 106. Device servers that implement the LOG SELECT command shall also implement
the LOG SENSE command. Structures in the form of log parameters within log pages are defined as a way to
manage the log data. The LOG SELECT command provides for sending zero or more log pages via the Data
Out Buffer in the Log Page Format of Table 110. These Log Pages contain parameters that command the drive
to change selected threshold, or cumulative values of any or all drive logs. This section defines the format
The following tables in this section, and those in Section 8.9 that apply for the LOG SELECT command, show
functions that command the drive to perform or enable for performance, control parameter bits the drive shall
set/reset/save, log counts that shall be kept, etc. The list of Log pages supported is given in Table 113.
For the LOG SENSE command (see Section 8.9), the tables there 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. Although Section 8.9 describes the LOG SENSE command, the tables of that section
that apply to the LOG SELECT command are not repeated here in this section. Also, though the language of
the descriptions in Section 8.9 is for the LOG SENSE case, they apply to the LOG SELECT case similarly,
unless noted otherwise.
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
command) that affect initiators other than the initiator that sent the LOG SELECT command, the drive gener-
ates a REUNIT 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 will not execute and a CHECK CONDITION status will be issued by the drive. A REQUEST SENSE
command would normally follow and a REUNIT ATTENTION condition sense code would 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 7.6.6, REUNIT ATTENTION condition.
Table 106:
LOG SELECT command (4Ch)
Bit
7
Byte
0
1
2
PC [4]
3
Reserved
4
Reserved
5
Reserved
6
Reserved
7
(MSB)
8
9
CONTROL [6]
[1]
Formerly LOGICAL UNIT NUMBER.
[2]
A Parameter Code Reset (PCR) bit of one and a PARAMETER LIST LENGTH of zero causes all imple-
mented parameters to be set to the drive-defined default values (most likely zero). If the PCR bit is one
and the PARAMETER LIST LENGTH is greater than zero, the command is terminated with a 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. A PCR bit of zero specifies that the log parameters shall not be reset.
[3]
A Save Parameters (SP) bit of one indicates that after performing the specified LOG SELECT operation
the drive shall save to non-volatile memory all LOG SELECT parameters identified as savable by the DS
bit in the Log parameter sections of the Log page (see Tables 110 and 111). An SP bit of zero specifies
6
5
OPERATION CODE (4Ch)
Reserved [1]
PARAMETER LIST LENGTH [5]
4
3
Reserved
2
1
PCR [2]
SP [3]
(LSB)
171
0
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