SAM2:SCSI client server model

Jim Hafner hafner at almaden.ibm.com
Tue Oct 2 15:24:01 PDT 2001


* From the T10 Reflector (t10 at t10.org), posted by:
* "Jim Hafner" <hafner at almaden.ibm.com>
*

Sanjeev,
I'll try to take a stab at this.

The short answer to your question is NO.  There is no relationship between
the iSCSI connection/session (and FC login) and the application client.

The I_T nexus is between a SCSI Initiator Port and a SCSI Target Port.
That can live as a relationship as long as the transport layer wants to
keep it (or even pretend that it is there).

The application client sits above the SCSI Initiator Port.  It is created
when a SCSI task needs handling, is encapsulated by CDB or task management
function and handed to the SCSI Initiator Port for delivery.  When status
is returned, the application client goes away.  It's been called a "thread
of execution" of a single SCSI task.  While it may come and go, the SCSI
Initiator Port and SCSI Target Port may stay and any relationship (like
login) between them may stay in place as well.

In short, the application client is above the SCSI Initiator Port and the
session is below the port (in the implementation of the port's interface to
the transport).

Does that help?

Jim Hafner


"Sanjeev Bhagat \(TRIPACE/Zoetermeer\)" <iscsi_t10 at sanjeevbhagat.com>
@t10.org on 10/02/2001 01:37:31 pm

Sent by:  owner-t10 at t10.org


To:   "T10 Reflector" <t10 at t10.org>
cc:
Subject:  SAM2:SCSI client server model



* From the T10 Reflector (t10 at t10.org), posted by:
* "Sanjeev Bhagat \(TRIPACE/Zoetermeer\)" <iscsi_t10 at sanjeevbhagat.com>
*
Refer to SAM2r20, section 4.3, page 29
In the architecture model , an application client is created to issua a
single SCSI command or task management function. An application client
ceases to exist once the command or or task management function ends.

also section 4.7.3 page 27
This model assumes that there is one application client for each pending
command or task management function.

Does the above two lines imply that everytime an application client wants
to
send a command to the target it will have to start a new connection and
session and end it as the command ends??


Regards,
Sanjeev

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