From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: READ CAPACITY 16 Date: Wed, 17 Dec 2008 12:32:38 -0700 Message-ID: <20081217193237.GG19967@parisc-linux.org> References: <20081217164210.GC19967@parisc-linux.org> <20081217180640.GE19967@parisc-linux.org> <1229540692.3508.18.camel@localhost.localdomain> <20081217191135.GF19967@parisc-linux.org> <1229541249.3508.24.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from palinux.external.hp.com ([192.25.206.14]:37951 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751250AbYLQTcz (ORCPT ); Wed, 17 Dec 2008 14:32:55 -0500 Content-Disposition: inline In-Reply-To: <1229541249.3508.24.camel@localhost.localdomain> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Grant Grundler , linux-scsi@vger.kernel.org On Wed, Dec 17, 2008 at 02:14:09PM -0500, James Bottomley wrote: > On Wed, 2008-12-17 at 12:11 -0700, Matthew Wilcox wrote: > > On Wed, Dec 17, 2008 at 02:04:52PM -0500, James Bottomley wrote: > > > Actually, we can't afford to send READ CAPACITY(16) to failing devices; > > > some of them never come back. > > > > When you say 'never come back', do you mean: > > > > a) The drive discards the command silently > > b) The drive hangs until a reset is issued > > c) The drive hangs until it's power-cycled > > d) The drive turns into a paperweight > > All of the above ... this is USB ... well, I don't *know* of a D > case ... but I wouldn't bet one doesn't exist. The unfortunate thing is that we don't have a collection of INQUIRY results from these devices, so we can't say whether checking for SCSI_2 would eliminate those in categories C and D. Are you willing to take a patch that sends RC16 for devices claiming SCSI_2, and falls back to RC10 if that doesn't work? Or shall I try to implement algorithm D and talk to T10? -- 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."