From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757684AbXGISKG (ORCPT ); Mon, 9 Jul 2007 14:10:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753807AbXGISJz (ORCPT ); Mon, 9 Jul 2007 14:09:55 -0400 Received: from iriserv.iradimed.com ([72.242.190.170]:29096 "EHLO iradimed.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753600AbXGISJy (ORCPT ); Mon, 9 Jul 2007 14:09:54 -0400 Message-ID: <469279EA.4020702@cfl.rr.com> Date: Mon, 09 Jul 2007 14:09:46 -0400 From: Phillip Susi User-Agent: Thunderbird 1.5.0.12 (Windows/20070509) MIME-Version: 1.0 To: Kent Overstreet CC: Linux Kernel Mailing List Subject: Re: [RFC] LVM/RAID/FS integration References: <6f703f960706271609m6fdfb9c1ha3555a68fe1d9d55@mail.gmail.com> In-Reply-To: <6f703f960706271609m6fdfb9c1ha3555a68fe1d9d55@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 09 Jul 2007 18:10:06.0030 (UTC) FILETIME=[60CAE6E0:01C7C254] X-TM-AS-Product-Ver: SMEX-7.5.0.1243-5.0.1021-15288.000 X-TM-AS-Result: No--4.623600-5.000000-2 X-TM-AS-User-Approved-Sender: No X-TM-AS-User-Blocked-Sender: No Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Kent Overstreet wrote: > The trouble is it's completely impractical with current tools; we need > tighter integration between md and LVM. Basically, we need a new type > of VG; you'd only be able to make it out of PVs that are the same size > (or close). Then, when you create an LV you decide what kind of > redundancy you want; the LVM internally creates multiple LVs and raids > them together to make the LV the fs sees. In theory LVM is meant to handle the raid bits as well, once the mirror target is improved to properly handle error correction, and the raid5 target stabilizes. Thus md won't be needed, you will just need an interface between the filesystem and lvm. > This could, sort of, be done in userspace, but I think it'll work > better if dm and md are better integrated in the kernel. I thought i'd > throw out my ideas before I get too far in. Thoughts? This is the kind of thing that should go in userspace. The filesystem should just fire off events that tell a userspace daemon things like "the raid5 volume is now at x% use" and let it choose the policy, possibly by asking lvm to resize the underlying volume, then sending a message back to the fs that the volume has been resized, and it can start using the extra space.