RE: iSCSI: multiple sessions b/n a pair of WWUIs.

[Black_David@emc.com]

While Jim's correct ... in Marj's defense, what
she wrote is a fairly obvious way to implement
it, and that might be worth noting in the draft.

--David

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David L. Black, Senior Technologist
EMC Corporation, 42 South St., Hopkinton, MA  01748
+1 (508) 435-1000 x75140     FAX: +1 (508) 497-8500
black_david@emc.com       Mobile: +1 (978) 394-7754
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> -----Original Message-----
> From:	Jim Hafner [SMTP:hafner@almaden.ibm.com]
> Sent:	Monday, May 07, 2001 10:44 PM
> To:	KRUEGER,MARJORIE (HP-Roseville,ex1)
> Cc:	ips@ece.cmu.edu
> Subject:	RE: iSCSI: multiple sessions b/n a pair of WWUIs.
> 
> 
> Marj,
> 
> I think you've stretched my words too far.  The requirement is for a
> single
> logical unit to recover enough identity information provided through the
> I_T_L nexus to reestablish the reservation.  That means that the name+ISID
> must be unique *from the viewpoint of a single iSCSI target device*.  So
> it's more like the
> "initiator must have unique ISID for all sessions with <delete>all
> targets</delete> any given target device".
> 
> The best way to think about this is the following:
> 1) only a single target's (actually logical unit's) view of the initiator
> counts in this regard
> 2) there are no rules in SCSI concerning multi-target device interactions
> In other words, for these rules, look only from inside a target going out.
> 
> Jim Hafner
> 
> 
> "KRUEGER,MARJORIE (HP-Roseville,ex1)"
> <marjorie_krueger@hp.com>@ece.cmu.edu
> on 05/04/2001 05:39:35 PM
> 
> Sent by:  owner-ips@ece.cmu.edu
> 
> 
> To:   "'Matt Wakeley'" <matt_wakeley@agilent.com>, ips@ece.cmu.edu
> cc:
> Subject:  RE: iSCSI: multiple sessions b/n a pair of WWUIs.
> 
> 
> 
> > One clarification: these are unique between any I-T *pair*.
> > (you make it sound like an initiator must have a unique ISID
> > for all sessions
> > with all targets)
> >
> > -Matt
> 
> The ISID must be unique within the iSCSI layer on an iSCSI device - that
> amounts to "initiator must have unique ISID for all sessions with all
> targets".
> 
> To quote Jim "The requirement in name+disc that a given initiator name
> cannot reuse an ISID for two different sessions comes as a consequence a
> number of things (which are described in the draft).  The gist is that
> this
> is needed to provide the correct context for restoration of reservations
> state (and other nexus state) to a particular nexus after logout/login. In
> other words, if the session goes down for some reason, the target needs
> clear context to restore nexus state to a rebuilt session. The only tool
> it
> has is uniqueness of Name+ISID combination within its name space."
> 
> -Marj
> 
>