RE: iSCSI: LUN in a ping

["Julian Satran" <Julian_Satran@il.ibm.com>]

The reason for having the LUN in all
incoming messages is not to help discovery but to enable "federated"
targets
to issue their TTTs without coordination
and add the LUN so that any outgoing message will be "routed"
to the right box.

However we realized early on that the
checking of the validity of the LUN by an initiator should be left to the
implementer.

That is why section 3.2.4.3 mandates
testing only where consistency with ITT is involved.

Julo

"Ken Craig" <kcraig@istor.com>
Sent by: owner-ips@ece.cmu.edu

23/01/03 21:01

To	Julian Satran/Haifa/IBM@IBMIL
cc	<ips@ece.cmu.edu>
Subject	RE: iSCSI: LUN in a ping

Hello Julo,
 
For those of us that weren't here
18 months ago can you refresh
us on your explanation or point
us to where it is since I too 
wonder why a SCSI Target would
not use the mechanisms it
already has in place to notify
an initiator of a LUN inventory
change?
 
Thanks,
Ken Craig
-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com] 
Sent: Thursday, January 23, 2003 8:47 AM
To: Eddy Quicksall
Cc: ips@ece.cmu.edu; Julian Satran; owner-ips@ece.cmu.edu; Rod Harrison
Subject: RE: iSCSI: LUN in a ping


Eddy, 

We all appreciate you opinion - but this has been hotly debated more than
18 months ago. 
And I recall sending you an explanation regarding the middle boxes and
how they handle the LUN for routing in a "clustered" target.
And your comment about a "requirement with no good reason" besides
being derogatory does not add any value to the discussion.

Julo

Eddy Quicksall <eddy_quicksall@ivivity.com>
Sent by: owner-ips@ece.cmu.edu

23/01/03 17:19

To	Rod Harrison <rod.harrison@windriver.com>, Julian Satran <julian@cs.haifa.ac.il>, ips@ece.cmu.edu
cc
Subject	RE: iSCSI: LUN in a ping

For that, wouldn't the target generate REPORTED LUNS DATA HAS CHANGED
(3F/0E)?

It is my opinion that this is just another requirement that has been put
on
the target for no good reason.

It should be up to the target as to if the LUN field has meaning and the
initiator should be the one that has a requirement to echo the value.

Eddy

-----Original Message-----
From: Rod Harrison [mailto:rod.harrison@windriver.com]
Sent: Wednesday, January 22, 2003 1:52 PM
To: Eddy Quicksall; Julian Satran; ips@ece.cmu.edu
Subject: RE: iSCSI: LUN in a ping



The initiator might try to rediscover the LUN topology if it sees a NOP
from
a
LUN that it previously thought was not present.

- Rod

-----Original Message-----
From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
Eddy Quicksall
Sent: Wednesday, January 22, 2003 10:28 AM
To: Julian Satran; Eddy Quicksall; ips@ece.cmu.edu
Subject: RE: iSCSI: LUN in a ping


Yes, I remember that but the necessity for the target to set it should
be up
to the target because the initiator should not be trying to interpret it
(it
should only be required to echo it).

Is there a case where the initiator will interpret the LUN?

Eddy

-----Original Message-----
From: Julian Satran [mailto:julian@cs.haifa.ac.il]
Sent: Wednesday, January 22, 2003 12:43 AM
To: 'Eddy Quicksall'; ips@ece.cmu.edu
Subject: RE: iSCSI: LUN in a ping


TTT & LUN uniquely identify the "origin" (if target is a
"composite"
each of the parts can issue their own TTTs - no coordination needed).

Regards,
Julo


-----Original Message-----
From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu] On Behalf Of
Eddy Quicksall
Sent: 22 January, 2003 00:07
To: ips@ece.cmu.edu
Subject: iSCSI: LUN in a ping


Does anyone know why we added "the LUN must be valid" for a target
initiated ping? It would seem that it is N/A when the ping is just being
used to checkup on the connection.

What will the initiator do with the LUN anyway?

10.19.3 LUN
A LUN MUST be set to a correct value when the Target Transfer Tag is
valid (not the reserved value 0xffffffff).

Eddy
mailto: Eddy_Quicksall@iVivity.com