From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758418Ab2DJSgc (ORCPT ); Tue, 10 Apr 2012 14:36:32 -0400 Received: from casper.infradead.org ([85.118.1.10]:53041 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753349Ab2DJSgb (ORCPT ); Tue, 10 Apr 2012 14:36:31 -0400 Message-ID: <4F847DAB.5030707@kernel.dk> Date: Tue, 10 Apr 2012 20:36:27 +0200 From: Jens Axboe MIME-Version: 1.0 To: Mike Snitzer CC: Vivek Goyal , linux kernel mailing list , martin.petersen@oracle.com Subject: Re: [RFC PATCH] block: Change default IO scheduler to deadline except SATA References: <20120410133708.GE21801@redhat.com> <4F843C17.5050004@kernel.dk> <20120410142148.GG21801@redhat.com> <20120410151042.GH21801@redhat.com> In-Reply-To: X-Enigmail-Version: 1.4 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2012-04-10 18:13, Mike Snitzer wrote: > That said, we can have a _very_ good hint that a SCSI device is a raid array if: > > 1) optimal_io_size is not zero, minimum_io_size is not equal to > optimal_io_size, and optimal_io_size is a multiple of minimum_io_size > > 2) WCE=0 (higher-end arrays with a writeback cache) Any other device than a basic SATA disk will have WCE=0. So I don't think that gives you a very good hint of the nature of it, unfortunately. -- Jens Axboe