From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 17 Jun 2002 12:42:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 17 Jun 2002 12:42:20 -0400 Received: from host194.steeleye.com ([216.33.1.194]:10771 "EHLO pogo.mtv1.steeleye.com") by vger.kernel.org with ESMTP id ; Mon, 17 Jun 2002 12:42:18 -0400 Message-Id: <200206171642.g5HGg5b03044@localhost.localdomain> X-Mailer: exmh version 2.4 06/23/2000 with nmh-1.0.4 To: Patrick Mansfield cc: James Bottomley , Oliver Neukum , David Brownell , Andries.Brouwer@cwi.nl, garloff@suse.de, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, sancho@dauskardt.de, linux-usb-devel@lists.sourceforge.net, linux1394-devel@lists.sourceforge.net, dougg@torque.net Subject: Re: [linux-usb-devel] Re: /proc/scsi/map In-Reply-To: Message from Patrick Mansfield of "Mon, 17 Jun 2002 09:09:58 PDT." <20020617090958.A19843@eng2.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Mon, 17 Jun 2002 11:42:05 -0500 From: James Bottomley X-AntiVirus: scanned for viruses by AMaViS 0.2.1 (http://amavis.org/) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org patmans@us.ibm.com said: > I agree it would be nice to get the ID via user space, but it is not > that hard to get the ID, and trying the various SCSI INQUIRY pages > that supply the ID is not complicated. OK, how about some hardware scenarios: I've a scsi array (an LSI 6298) which has no WWN page (0x83) but does have a serial number in the VPD page. However, the VPD serial number is an identifier for the array *controller* and thus is the *same* for all the LUNs. For this beast I have to add in the LUN number to the VPD serial number to get a unique identifier per device. Worse, the LSI 6298 is multi path. Now I get a different "unique" identifier depending on path (because different controllers give different VPD serial numbers), so if I want to identify it uniquely, I have to use some property of the LUN, like partion UUID. Or, what about an old 8 bit EMC symmetrix. They have no WWN page and they embed both a LUN and a *path* identifier in the VPD serial number. To get the globally unique ID for this one, I have to strip off the path part. > FYI the various SCSI ID pages and such are described in the SCSI > primaray command for example the following: > ftp://ftp.t10.org/t10/drafts/spc3/spc3r07.pdf Ah, but that's the scsi-3 spec which (finally) cleaned up this unique name business. However, for SCSI-2 and before, it was an unholy mess, as the two examples above illustrate. I agree that for all modern devices which are SCSI-3 SPC compliant, then just asking for the WWN page probably works. The question is what to do about all the legacy hardware out there? James