Dell PowerVault TL4000 SCSI Reference Guide - Page 101

Command, Complete, Extended, messages

Get Dell PowerVault TL4000 PDF manuals and user guides View all Dell PowerVault TL4000 manuals
Add to My Manuals
Save this manual to your list of manuals

Page 101 highlights

Chapter 4. Messages The message system allows communication between the host and the media changer logical unit for the purpose of physical path management. Description COMMAND COMPLETE EXTENDED MESSAGES SAVE DATA POINTERS RESTORE POINTERS DISCONNECT INITIATOR DETECTED ERROR ABORT MESSAGE REJECT NO-OP MESSAGE PARITY ERROR BUS DEVICE RESET IDENTIFY Code 00h 01h 02h 03h 04h 05h 06h 07h 08h 09h 0Ch 80h / C0h Direction In In / Out In In In Out Out In / Out Out Out Out In / Out Command Complete The COMMAND COMPLETE message is sent from a target to an initiator to indicate that the execution of a command completed and a valid status has been sent to the initiator. Extended messages The library supports two extended messages: Synchronous Data Transfer Request (01h) and Wide Data Transfer Request (03h). All other extended messages are rejected with a Reject message after receiving the entire Extended message. The SDTR is used to negotiate data transfer agreements. If the host wants to transfer data synchronously it must negotiate a synchronous data transfer agreement with the target before transferring data. The media changer does not support synchronous data transfer. When it receives a SDTR from a initiator, it returns a SDTR message with a REQ/ACK offset equal to zero. This indicates that the media changer requires asynchronous data transfer. Bit 7 6 5 4 3 2 1 0 Byte 0 Extended Message (01h) 1 Extended Message Length (03h) 2 Extended Message Code (01h) 3 Transfer Period Factor 4 REQ/ACK Offset The Transfer Period Factor field indicated the value for the Transfer Period in 4ns counts. This value is not used, the returned value is 00h. The media changer returns 00h for the REQ/ACK Offset field indicating that the media changer requires asynchronous data transfer. 4-1

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
Chapter
4.
Messages
The
message
system
allows
communication
between
the
host
and
the
media
changer
logical
unit
for
the
purpose
of
physical
path
management.
Description
Code
Direction
COMMAND
COMPLETE
00h
In
EXTENDED
MESSAGES
01h
In
/
Out
SAVE
DATA
POINTERS
02h
In
RESTORE
POINTERS
03h
In
DISCONNECT
04h
In
INITIATOR
DETECTED
ERROR
05h
Out
ABORT
06h
Out
MESSAGE
REJECT
07h
In
/
Out
NO-OP
08h
Out
MESSAGE
PARITY
ERROR
09h
Out
BUS
DEVICE
RESET
0Ch
Out
IDENTIFY
80h
/
C0h
In
/
Out
Command
Complete
The
COMMAND
COMPLETE
message
is
sent
from
a
target
to
an
initiator
to
indicate
that
the
execution
of
a
command
completed
and
a
valid
status
has
been
sent
to
the
initiator.
Extended
messages
The
library
supports
two
extended
messages:
Synchronous
Data
Transfer
Request
(01h)
and
Wide
Data
Transfer
Request
(03h).
All
other
extended
messages
are
rejected
with
a
Reject
message
after
receiving
the
entire
Extended
message.
The
SDTR
is
used
to
negotiate
data
transfer
agreements.
If
the
host
wants
to
transfer
data
synchronously
it
must
negotiate
a
synchronous
data
transfer
agreement
with
the
target
before
transferring
data.
The
media
changer
does
not
support
synchronous
data
transfer.
When
it
receives
a
SDTR
from
a
initiator,
it
returns
a
SDTR
message
with
a
REQ/ACK
offset
equal
to
zero.
This
indicates
that
the
media
changer
requires
asynchronous
data
transfer.
Bit
7
6
5
4
3
2
1
0
Byte
0
Extended
Message
(01h)
1
Extended
Message
Length
(03h)
2
Extended
Message
Code
(01h)
3
Transfer
Period
Factor
4
REQ/ACK
Offset
The
Transfer
Period
Factor
field
indicated
the
value
for
the
Transfer
Period
in
4ns
counts.
This
value
is
not
used,
the
returned
value
is
00h.
The
media
changer
returns
00h
for
the
REQ/ACK
Offset
field
indicating
that
the
media
changer
requires
asynchronous
data
transfer.
4-1