Subject: Re: iSCSI Naming: WWUIs, URNs, and namespaces

From: "Thomas McSweeney" <[email-masked]>
Date: Wed, 11 Apr 2001 16:13:50 -0400

Brian,

>Are "initiators" being connected to actively by "targets"?
>Via some call back or something?

Not that I know of.  The target has to map each initiator that is logging
in to a particular SCSI resource (or set of resources), which may be
different for each initiator.  For example, suppose you have an iSCSI
target node with disk space carved up evenly between two users.  When you
log in to that target, you want to be given access to your disk space
allocation, not mine.  The initiator identifies itself to the target via
the InitiatorWWUI text key of the Login.  The current spec declares that
InitiatorWWUI is globally unique, which makes this mapping easy.  If
InitiatorWWUI is unique only within the initiator node, multiple initiator
nodes can choose the same name (e.g., "WindowsLaptop").  We'll have to
qualify it with something else to make it unique, at least to a target that
uses that name to look up the mapping.

Tom McSweeney
iSCSI Development, Storage Systems Group, IBM
Email: [email-masked]
Phone: (USA) 919-254-5634  (tie line: 444-5634)
Fax:   (USA) 919-254-0391  (tie line: 444-0391)

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From: "Douglas Otis" <[email-masked]>
Date: Wed, 11 Apr 2001 16:41:56 -0700

Thomas,

Part of the justification for creating a new name server was to promulgate
changes to various consumers.  If you look at the food chain involved in the
iSCSI to SCSI configuration, the iSCSI server is a principle consumer
whereas the iSCSI clients need this transitory information to pass to iSCSI
server.  Would you see an advantage in having a type of housekeeping signal
to be incorporated within the iSCSI protocol to signal a need to update
configuration information?  Management software that changes the information
could advise the iSCSI servers that in turn through the use of the protocol
signals, advise their clients.  It would seem this system naturally scales
better than a scheme that expects all clients to retain a persistent but
otherwise idle connection to a name server.  I can think of a few more cases
where this same management software may wish to advise of such a change in
advance as well as to advise after the fact.

Doug