Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932341AbdCGP0j (ORCPT ); Tue, 7 Mar 2017 10:26:39 -0500 Received: from mail-it0-f66.google.com ([209.85.214.66]:34176 "EHLO mail-it0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755531AbdCGP0b (ORCPT ); Tue, 7 Mar 2017 10:26:31 -0500 Subject: Re: When will Linux support M2 on RAID ? To: Christoph Hellwig , "David F." References: <20170307045200.GA1708@infradead.org> Cc: linux-kernel , "linux-raid@vger.kernel.org" From: "Austin S. Hemmelgarn" Message-ID: Date: Tue, 7 Mar 2017 09:50:22 -0500 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20170307045200.GA1708@infradead.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1301 Lines: 24 On 2017-03-06 23:52, Christoph Hellwig wrote: > On Sun, Mar 05, 2017 at 06:09:42PM -0800, David F. wrote: >> More and more systems are coming with M2 on RAID and Linux doesn't >> work unless you change the system out of RAID mode. This is becoming >> more and more of a problem. What is the status of Linux support for >> the new systems? > > Your message doesn't make sense at all. MD works on absolutely any > Linux block device, and I've used it on plenty M.2 form factor devices - > not that the form factor has anything to do with how Linux would treat > a device. > He's referring to the RAID mode most modern Intel chipsets have, which (last I checked) Linux does not support completely and many OEM's are setting by default on new systems because it apparently provides better performance than AHCI even for a single device. The bigger issue with this is that it's damn near impossible to get to the firmware on many new systems, and even if you can, some OEM's aren't even giving the option to use AHCI mode instead of the RAID mode. The whole M.2 thing is absolutely bogus though, my thought is that people are conflating the two because this switch to using RAID mode by default is happening concurrently with a general movement towards using M.2 devices as primary storage.