Subject: RE: [Ips] IPS WG last call on iSCSI Name Extension Draft

From: [email-masked]
Date: Thu, 19 Feb 2004 19:21:22 -0500

A bit later than I had hoped, I've reviewed this draft,
and turned up what I believe to be a serious issue.

Section 2 of the draft motivates NAA naming for iSCSI by
discussing the naming formats used by four SCSI transports:
iSCSI, Fibre Channel (FC), Serial Attach SCSI (SAS), and SCSI
RDMA Protocol (SRP).  At first blush, it says that iSCSI should
support NAA naming so that it has at least one naming format
in common with each of the other three SCSI transports.

Probing deeper, it appears that:
- SRP provides no motivation for NAA because SRP already
	uses EUI-64.  Mentioning SRP could lead the less than
	expert reader to the incorrect conclusion that iSCSI is
	being modified to accommodate InfiniBand.  I think the SRP
	material is extraneous and should be deleted for this
	reason.
- The Fibre Channel motivation seems to be based on a hope that
	T10 will do something in the future about using NAA for
	SCSI device names (the Note in square brackets).  That's
	questionable for a standards track RFC.  If the FC
	motivation for NAA usage in iSCSI requires that T10 do
	something, then we should wait until T10 does that so
	that we have a stable T10 doc (FCP-3 draft?) to refer to.

So, Section 2 appears to boil down to introducing the new
NAA naming format to iSCSI to accommodate SAS (Serial Attach
SCSI) in a multi-protocol SCSI device, but that's not an easy
conclusion to draw from the text as it is currently written.

If what I've written above is essentially correct, Section 2
needs to be rewritten to clearly state that SAS is the primary
motivation for adding NAA names to iSCSI or to provide the
stable T10 reference for FC NAA device naming to use FC as a
motivation.

Given the difficulty in figuring out the technical case
for NAA naming as the draft is currently written, another
WG Last Call may be needed on a version of the
draft with a rewritten Section 2.  Elizabeth and I have
sent a number of other editorial comments to the authors.

I apologize for the delay in getting to this.

--David
----------------------------------------------------
David L. Black, Senior Technologist
EMC Corporation, 176 South St., Hopkinton, MA  01748
+1 (508) 293-7953             FAX: +1 (508) 293-7786
[email-masked]        Mobile: +1 (978) 394-7754
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