Re: iSCSI: naming/LUN views

[Mark Bakke <mbakke@cisco.com>]

Pierre-

Sorry I took so long to reply; for some reason, I didn't receive
your original message from the reflector.

I agree with all of Jim's comments, but would state this one
more strongly:

  A TargetWWUI MUST present exactly the same LU view to an
  InitiatorWWUI regardless of the portal on which it is accessed.

This means that we have a method of identification at the target
level, which we were missing (at least as a standard) from FC and
parallel SCSI.

This was our intent, and would solve the problem you stated of
having to compare views.  Perhaps we should add this statement
to the document.

--
Mark

Jim Hafner wrote:
> 
> Pierre,
> 
> In my view, one should get the same LU view in your situation because there
> is effectively no other information by which the target might present a
> different view.  Namely, the target (that creates/enforces the view) is the
> entity scoped by the TargetWWUI.  It uses the Initiator WWUI to construct
> that LU view.  That might be constructed by rules established via SCSI
> access controls (and yes, the InitiatorWWUI is the right mapping to
> TransportID though that has not been formalized anywhere yet).
> 
> This has some interesting implications.  Within the context of a single
> SESSION established through multiple connections, there is only the one I_T
> nexus.  But we can also establish multiple sessions between the same
> InitiatorWWUI and TargetWWUI.  As far as access controls are concerned, the
> views should be identical.  As for other properties of I_T nexus', e.g.,
> reservations, the jury is still out.
> 
> Jim Hafner
> 
> Pierre Labat <pierre_labat@hp.com>@ece.cmu.edu on 02-27-2001 10:38:26 AM
> 
> Sent by:  owner-ips@ece.cmu.edu
> 
> To:   ips@ece.cmu.edu
> cc:
> Subject:  iSCSI: naming/LUN views
> 
> Mark (Bakke),
> 
> After going through the naming/discovery drafts,
> a question came to my mind:
> 
> Does several connections flowing through
> several portals but using  the same initiator WWUI
> and target WWUI will see the same thing on the target?
> I mean by same thing: same LUs associated to the same LUNs.
> 
> I guess that the initiator WWUI acts as an transportID (SCSI access
> control)
> and gives the same LUs view independently of the portal used.
> Is it the case?
> 
> If it is not the case, the entity that creates multiconnections
> sessions
> will need out of band information to know if the  2 portals can be used
> for a same session or will have to do the  painfull job to compare the
> LU views
> from the two portals with no guarantee that the views could not change
> in the future.
> 
> Regards,
> 
> Pierre

-- 
Mark A. Bakke
Cisco Systems
mbakke@cisco.com
763.398.1054