From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH 5 of 8] sd: Detect non-rotational devices Date: Thu, 23 Apr 2009 08:16:44 -0600 Message-ID: <20090423141644.GP1926@parisc-linux.org> References: <20090423105245.GX4593@kernel.dk> <49F04C71.6050304@garzik.org> <20090423113841.GK1926@parisc-linux.org> <49F06E3B.104@garzik.org> <1240495814.3514.8.camel@mulgrave.int.hansenpartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from palinux.external.hp.com ([192.25.206.14]:45381 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755475AbZDWOQp (ORCPT ); Thu, 23 Apr 2009 10:16:45 -0400 Content-Disposition: inline In-Reply-To: <1240495814.3514.8.camel@mulgrave.int.hansenpartnership.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: James Bottomley Cc: Jeff Garzik , "Martin K. Petersen" , Jens Axboe , rwheeler@redhat.com, snitzer@redhat.com, neilb@suse.de, dgilbert@interlog.com, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org On Thu, Apr 23, 2009 at 02:10:13PM +0000, James Bottomley wrote: > I'm with Jeff on this one. We had an identically similar problem with > REPORT LUNS, which, today is the basis of SCSI discovery. Yes, REPORT LUNS is quite essential. It's not exactly in the same category as reporting device form factor and rotational speed. If REPORT LUNS is wrong, we're in really deep trouble. If device form factr is wrong ... umm ... nothing much happens. If rotational speed is wrong, we might have a suboptimal IO pattern. It's also fixable by udev. The current check for is_ssd (that doesn't check the version) was put in for 2.6.27. It doesn't appear to have caused any trouble. -- 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."