Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1766636AbXEBTTA (ORCPT ); Wed, 2 May 2007 15:19:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1766637AbXEBTTA (ORCPT ); Wed, 2 May 2007 15:19:00 -0400 Received: from ug-out-1314.google.com ([66.249.92.171]:41766 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1766636AbXEBTS6 (ORCPT ); Wed, 2 May 2007 15:18:58 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=gV0diPHrVr83J/2Dtho7fRSjU9IBNClGRalLf1remMXrnJGubE9UEKwraghkHpgwTPEDGzHb7yeCfM8gX8VoZxy1nlMQDlnicubUHy/agbAOfsnn1CGHdtxOFsC2disqsbu60npc3Jj2QxozI/CSSNLjuMnuawhnQwIxIoeaRug= Message-ID: Date: Wed, 2 May 2007 20:18:55 +0100 From: "Miguel Sousa Filipe" To: linux-kernel@vger.kernel.org Subject: FEATURE REQUEST: merge MD software raid and LVM in one unique layer. In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2565 Lines: 70 Hello kernel hackers, Some weeks ago, in a ZFS related thread, some kernel hackers asked the user what did they liked in ZFS that linux didn't have, so that they could (possibly) work on it. So, here is my feature request: - merge MD software raid framework and LVM in one unique API/framework, to be controled/managed by one unique userland toolset. Any sysadmin which needs to do device & volume management and FS management in Linux has do use three diferent tools, for 3 diferent layers (that I think shouldn't be 3 layers.. but only 2). - md : MD is a software raid framework, with raid0, 1, 4, 5, 6, append and others.. - lvm : The logical volume manager: this allows you to manage logical disks (devices), grow a device, add phisical devices to a existing volume, snapshot.. etc.. - fs duh... the FileSystem level. However, MD and LVM have feature replications: - raid1 / mirroring - raid0 / stripping - append / concatenate I find it high irritanting having two kernel interfaces and two userland tools that provide the same funcionality, which one should I use? I also don't understand from the point of view of code maintenance.. shurely there is some unneeded duplicate code lying in the kernel tree. One of the good things (my opinion) about ZFS is putting these things in one unique place, with a good user interface (the zpool & other zfs command tools are quite easy and simple to use). On linux, I find myself having to setup each layer by hand, each with its own peculiarities and command line tools.. I consede that maybe the FS layer and the device management layer shouldn't be merged. But clearly that in Linux we have too different layers (that aren't really layers since they do not depend on one another) for the same purpose: - device manangement. I'm no kernel hacker, I'm just a simple user, but this is my *pretty please* that some kernel hackers work together to unite and simplify the work that has to be made to use software raid and volume management on Linux. In essence, I believe that bringing the funcionality that is unique to MD integrated in LVM would suffice (leaving MD there for legacy compat.. but warning users about future improvements on LVM only) Thank you very much, PS: I'm not subscribed to lkml yet, please CC me any reply -- Miguel Sousa Filipe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/