From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753886AbXC0O1D (ORCPT ); Tue, 27 Mar 2007 10:27:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753885AbXC0O1D (ORCPT ); Tue, 27 Mar 2007 10:27:03 -0400 Received: from ottawa-hs-64-26-128-89.s-ip.magma.ca ([64.26.128.89]:2430 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753881AbXC0O1A (ORCPT ); Tue, 27 Mar 2007 10:27:00 -0400 Message-ID: <460929B3.60303@rtr.ca> Date: Tue, 27 Mar 2007 10:26:59 -0400 From: Mark Lord User-Agent: Thunderbird 1.5.0.10 (X11/20070221) MIME-Version: 1.0 To: Jeff Garzik Cc: Justin Piszcz , linux-kernel@vger.kernel.org, IDE/ATA development list Subject: Re: Why is NCQ enabled by default by libata? (2.6.20) References: <4608B2B9.7090503@garzik.org> In-Reply-To: <4608B2B9.7090503@garzik.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jeff Garzik wrote: > > In some cases, NCQ firmware may be broken. There is a Maxtor firmware > id, and some Hitachi ids that people are leaning towards recommending be > added to the libata 'horkage' list. Western Digital "Raptor" drives (the 10K rpm things) are also somewhat borked in NCQ mode, depending on the application. Their firmware turns off all drive readahead during NCQ. This makes them very good for an email/news server application, but also causes them to suck for regular desktop applications. Because of this, they use special software drivers under MSwin which detect large sequential accesses, and avoid NCQ during such times. Cheers -ml