Log sense (4dh), Sense, 4dh) – Dell PowerVault TL4000 User Manual

Page 25

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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