Dell PowerVault TL4000 SCSI Reference Guide - Page 25

Sense

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LOG SENSE (4Dh) The LOG SENSE command allows the host to retrieve statistical information maintained by the media changer about its own hardware. The statistical information is divided over several pages. A LOG SENSE command will retrieve one of these pages. Byte 0 1 2 3 4 5 6 7 8 9 Bit 7 (MSB) (MSB) 6 LUN PC 5 4 3 2 Operation Code (4Dh) Reserved Page Code Reserved Reserved Parameter pointer Allocation length Control 1 0 PPC (0) SP (0) (LSB) (LSB) Field descriptions: PPC: If Parameter Pointer Control bit is set, the target terminates the command with Check Condition status. The sense key is set to ILLEGAL REQUEST, and an additional sense code of INVALID FIELD IN CDB. SP: Saving Log Parameters (SP) is not supported. If the SP bit is set, the command is terminated with Check Condition status with the sense key set to ILLEGAL REQUEST, and an additional sense code of INVALID FIELD IN CDB. PC: The Page Control field defines the type of parameter value to be returned. This field should either be set to 00b (Current Threshold Values) or 01b (Current Cumulative Values). If not, the command is terminated with Check Condition status with the sense key set to ILLEGAL REQUEST, and an additional sense code of INVALID FIELD IN CDB. The Current Cumulative Values are the values computed since the last reset of the device (either by power-cycling, Bus Device Reset, or SCSI Reset). Note: Only Log Sense Tape Alert page (2Eh) supports PC being set to Current Threshold Values. Page Code: The Page Code field identifies which log page is being requested by the initiator. If the page is not supported then the command terminates with a Check Condition status with the sense key set to ILLEGAL REQUEST, and an additional sense code of INVALID FIELD IN CDB. Supported pages are: v 00h -List of Supported Pages Page v 07h -Event Log Page v 2Eh -Tape Alert Page v 30h -Statistics Counter Page v 33h -Error Log Page Parameter Pointer: The Parameter Pointer field allows the host to specify at which parameter within a Log Page the requested data should begin. This is not supported in any Log Sense page and should be set to 0. Chapter 3. Supported SCSI Commands 3-11

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LOG
SENSE
(4Dh)
The
LOG
SENSE
command
allows
the
host
to
retrieve
statistical
information
maintained
by
the
media
changer
about
its
own
hardware.
The
statistical
information
is
divided
over
several
pages.
A
LOG
SENSE
command
will
retrieve
one
of
these
pages.
Bit
7
6
5
4
3
2
1
0
Byte
0
Operation
Code
(4Dh)
1
LUN
Reserved
PPC
(0)
SP
(0)
2
PC
Page
Code
3
Reserved
4
Reserved
5
(MSB)
Parameter
pointer
6
(LSB)
7
(MSB)
Allocation
length
8
(LSB)
9
Control
Field
descriptions:
PPC:
If
Parameter
Pointer
Control
bit
is
set,
the
target
terminates
the
command
with
Check
Condition
status.
The
sense
key
is
set
to
ILLEGAL
REQUEST,
and
an
additional
sense
code
of
INVALID
FIELD
IN
CDB.
SP:
Saving
Log
Parameters
(SP)
is
not
supported.
If
the
SP
bit
is
set,
the
command
is
terminated
with
Check
Condition
status
with
the
sense
key
set
to
ILLEGAL
REQUEST,
and
an
additional
sense
code
of
INVALID
FIELD
IN
CDB.
PC:
The
Page
Control
field
defines
the
type
of
parameter
value
to
be
returned.
This
field
should
either
be
set
to
00b
(Current
Threshold
Values)
or
01b
(Current
Cumulative
Values).
If
not,
the
command
is
terminated
with
Check
Condition
status
with
the
sense
key
set
to
ILLEGAL
REQUEST,
and
an
additional
sense
code
of
INVALID
FIELD
IN
CDB.
The
Current
Cumulative
Values
are
the
values
computed
since
the
last
reset
of
the
device
(either
by
power-cycling,
Bus
Device
Reset,
or
SCSI
Reset).
Note:
Only
Log
Sense
Tape
Alert
page
(2Eh)
supports
PC
being
set
to
Current
Threshold
Values.
Page
Code:
The
Page
Code
field
identifies
which
log
page
is
being
requested
by
the
initiator.
If
the
page
is
not
supported
then
the
command
terminates
with
a
Check
Condition
status
with
the
sense
key
set
to
ILLEGAL
REQUEST,
and
an
additional
sense
code
of
INVALID
FIELD
IN
CDB.
Supported
pages
are:
v
00h
-List
of
Supported
Pages
Page
v
07h
-Event
Log
Page
v
2Eh
-Tape
Alert
Page
v
30h
-Statistics
Counter
Page
v
33h
-Error
Log
Page
Parameter
Pointer:
The
Parameter
Pointer
field
allows
the
host
to
specify
at
which
parameter
within
a
Log
Page
the
requested
data
should
begin.
This
is
not
supported
in
any
Log
Sense
page
and
should
be
set
to
0.
Chapter
3.
Supported
SCSI
Commands
3-11