ADT-2: SCSI Command IU to Initiator Only port

Kevin D Butt kdbutt at
Mon Nov 26 12:19:45 PST 2007

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07-438r0 suggests that we change "acts as" a SCSI target/initiator port to 
"is" a SCSI target/initiator port. and that we add the following to ADT-2:
If a port that does not support SCSI target functions receives a SCSI 
Command IU or a SCSI Task Management IU, then it shall transmit a NAK IU 
table 14) and discard the IU.
Note x: The exchange originator should not interpret this response as an 
indication that the port does not have SCSI target port capabilities, only 
that it does not have SCSI target port capabilities enabled at this time 
(see 4.1).
Discussion about "acts as" vs "is"
First, I think "acts as" is more correct than "is".  A port that is a SCSI 
target/initiator port (this term does not exist in SAM-4) acts as a SCSI 
initiator port and a SCSI target port. 
SAM-4 states:
Each instance of a SCSI Port class shall contain:
a) one SCSI target port that shall contain:
A) one task router;
b) one SCSI initiator port; or
c) both.
SAM-3 states:
3.1.94 SCSI initiator port: A SCSI initiator device object that acts as 
the connection between application clients
and the service delivery subsystem through which requests, indications, 
responses, and confirmations are routed.
In all cases when this term is used it refers to an initiator port or a 
SCSI target/initiator port <<operating as>> a SCSI
initiator port.
3.1.99 SCSI target port: A SCSI target device object that contains a task 
router and acts as the connection
between device servers and task managers and the service delivery 
subsystem through which indications and
responses are routed. When this term is used it refers to a SCSI target 
port or a SCSI target/initiator port <<operating
as>> a SCSI target port.
3.1.101 SCSI target/initiator port: A SCSI device resident object that has 
all the characteristics of a SCSI target
port and a SCSI initiator port.
Discussion about adding the suggested text:
The issue that this proposal intends to solve is that of a port receiving 
a command IU when that port is an initiator port only or that is an 
initiator/target port that has not yet been configured to act as a target 
port.  One of the concerns about what is returned is that the port 
initiating this command IU not take the rejection to mean that this port 
will never accept a command IU.
There are really two behaviors that a plausible.  One behavior is that 
mentioned in the proposal of the transport layer returning a NAK IU with a 
to treat the port as being a target port but not having a valid logical 
unit so the response would be at a higher layer.
It seems to me that returning a LOGICAL UNIT NOT CONFIGURED would be more 
accurate.  Further it does not imply that the logical unit does not exist 
or is not supported.  It just implies that it needs configured before it 
can be communicated with.  This is exactly the scenario we are in.  The 
one concern I have with this approach is that no LU exists and no 
well-known LU either.
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at 
"Banther, Michael" <michael.banther at> 
Sent by: owner-t10 at
11/26/2007 10:39 AM
"t10 at" <t10 at>
ADI-2 teleconference
The ADI-2 working group will hold an ad-hoc teleconference on 28 November 
2007 starting at 8:00 AM PST and concluding at 10:00 AM PST.  You can find 
the agenda, including contact details, at
Michael Banther
Tel. +44 117 312 9503
Hewlett-Packard Limited registered Office:
Cain Road, Bracknell, Berks RG12 1HN
Registered No: 690597 England
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