From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: READ CAPACITY 16 Date: Thu, 18 Dec 2008 07:08:51 -0700 Message-ID: <20081218140851.GI19967@parisc-linux.org> References: <20081217164210.GC19967@parisc-linux.org> <20081217180640.GE19967@parisc-linux.org> <494A1272.8040008@panasas.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from palinux.external.hp.com ([192.25.206.14]:33215 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750940AbYLROIw (ORCPT ); Thu, 18 Dec 2008 09:08:52 -0500 Content-Disposition: inline In-Reply-To: <494A1272.8040008@panasas.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Boaz Harrosh Cc: Grant Grundler , linux-scsi@vger.kernel.org On Thu, Dec 18, 2008 at 11:05:54AM +0200, Boaz Harrosh wrote: > Matthew Wilcox wrote: > >>> Algorithm B: > >>> > >>> Issue RC10 > >>> Issue RC16 > >>> -> If it succeeds, use its results in preference to those from RC10 > >>> -> If it fails, carry on with the results from RC10 > >>> -> If it times out, reset the device, carry on with the results from RC10 > >> I fail to see an effective difference between Algo A and B. > > > > Whether to issue an RC10 before issuing an RC16 or not. It matches what > > we currently do better (we currently issue an RC10 and then issue an > > RC16 if RC10 reports we have 0xffffffff LBAs). > > > > Sorry to barge in but I think this is the most practical solution and the one > to go to T10 with. > > If a (new) device supports RC16 it should return LBAs==0xffffffff for RC10 even > if it's capacity is smaller, to indicate an RC16 request. That breaks compatibility with older software that doesn't know that RC16 exists. > If LBAs!=0xffffffff and !SCSI_3 then do not risk RC16 unless a white list > or load parameter. > > Since you are going to T10 with this the white list should be, as you said > in other mail, zero length. I don't need to go to T10 for anything except Algorithm D. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."