From mboxrd@z Thu Jan 1 00:00:00 1970 From: Swen Schillig Subject: Re: [PATCH] zfcp: Report FCP LUN to SCSI midlayer Date: Mon, 25 Jun 2007 12:39:09 +0200 Message-ID: <200706251239.09755.swen@vnet.ibm.com> References: <200706191025.30986.swen@vnet.ibm.com> <20070622044035.GB5560@us.ibm.com> <1182521500.3923.49.camel@mulgrave.il.steeleye.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Return-path: Received: from mtagate5.de.ibm.com ([195.212.29.154]:63807 "EHLO mtagate5.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751396AbXFYKjh (ORCPT ); Mon, 25 Jun 2007 06:39:37 -0400 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate5.de.ibm.com (8.13.8/8.13.8) with ESMTP id l5PAdVe4379148 for ; Mon, 25 Jun 2007 10:39:31 GMT Received: from d12av01.megacenter.de.ibm.com (d12av01.megacenter.de.ibm.com [9.149.165.212]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v8.3) with ESMTP id l5PAdV5g1601542 for ; Mon, 25 Jun 2007 12:39:31 +0200 Received: from d12av01.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av01.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l5PAdUma031675 for ; Mon, 25 Jun 2007 12:39:30 +0200 In-Reply-To: <1182521500.3923.49.camel@mulgrave.il.steeleye.com> Content-Disposition: inline Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Mike Anderson , Christof Schmitt , linux-scsi@vger.kernel.org On Friday 22 June 2007 16:11, James Bottomley wrote: > On Thu, 2007-06-21 at 21:40 -0700, Mike Anderson wrote: > > James Bottomley wrote: > > > A proposal to display the correct form of the LUN would be useful if you > > > wish to make it? ... The problem is really that SAM specifies a > > > possible 4 level structure with 4 possible address methods per level. > > > > > > The well known LUNs should be simple; there are only three: Report Lun, > > > Access Controls and Target Log Pages. The rest we really need input on. > > > For instance, I could see the vendors wishing us to combine a > > > multi-level flat addressing space into a single logical unit number, > > > whereas I could see them wanting us to supply some sort of hierarchy for > > > the peripheral and logical unit methods of addressing. > > > > > > Since you're already using 2 level flat addressing, how do you want to > > > see that represented? > > > > James, why would we would not want to display the lun per SAM4 4.6.2 as > > suggested by Stefan in a previous comment. > > Because in a two LUN system, what was LUN 1 would then become LUN > 0x1000000000000 which looks a bit unpalatable. > > James > > > - Despite the issue whether we should display and/or use (sysfs !?) full blown 64bit values, so with leading zeros, you still have the option to display, for the single level addressing, the LUN as a 2 byte value as described in SAM4 4.6.2. So for your example this would be 0x0001 or 0x1, which is exactly what you'd like to see, right ? Only for 2+ level environment the 64bit representation comes into the play. And, because you were asking how we'd like that to be represented, I personally prefer a full blown 64bit hex value with leading zeros. It makes the comparison to internal structures/models easier and gets us a bit closer to the documented (SAM4) standard. ...and I think we all can deal with a few extra digits being displayed. Cheers Swen