From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heinz Mauelshagen Subject: Re: [PATCH 000 of 5] md: Introduction Date: Mon, 23 Jan 2006 10:44:18 +0100 Message-ID: <20060123094418.GX2801@redhat.com> References: <43D00FFA.1040401@cfl.rr.com> <17360.5011.975665.371008@cse.unsw.edu.au> <43D02033.4070008@cfl.rr.com> <17360.9233.215291.380922@cse.unsw.edu.au> <20060120183621.GA2799@redhat.com> <20060120225724.GW22163@marowsky-bree.de> <20060121000142.GR2801@redhat.com> <20060121000344.GY22163@marowsky-bree.de> <20060121000806.GT2801@redhat.com> <20060121001311.GA22163@marowsky-bree.de> Reply-To: mauelshagen@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20060121001311.GA22163@marowsky-bree.de> Sender: linux-raid-owner@vger.kernel.org To: Lars Marowsky-Bree Cc: Heinz Mauelshagen , Neil Brown , Phillip Susi , Jan Engelhardt , "Lincoln Dale (ltd)" , Michael Tokarev , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, "Steinar H. Gunderson" List-Id: linux-raid.ids On Sat, Jan 21, 2006 at 01:13:11AM +0100, Lars Marowsky-Bree wrote: > On 2006-01-21T01:08:06, Heinz Mauelshagen wrote: > > > > A dm-md wrapper would give you the same? > > No, we'ld need to stack more complex to achieve mappings. > > Think lvm2 and logical volume level raid5. > > How would you not get that if you had a wrapper around md which made it > into an dm personality/target? You could with deeper stacking. That's why I mentioned it above. > > Besides, stacking between dm devices so far (ie, if I look how kpartx > does it, or LVM2 on top of MPIO etc, which works just fine) is via the > block device layer anyway - and nothing stops you from putting md on top > of LVM2 LVs either. > > I use the regularly to play with md and other stuff... Me too but for production, I want to avoid the additional stacking overhead and complexity. > > So I remain unconvinced that code duplication is worth it for more than > "hark we want it so!" ;-) Shall I remove you from the list of potential testers of dm-raid45 then ;-) > > -- Regards, Heinz -- The LVM Guy -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Red Hat GmbH Consulting Development Engineer Am Sonnenhang 11 Cluster and Storage Development 56242 Marienrachdorf Germany Mauelshagen@RedHat.com +49 2626 141200 FAX 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-