Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753690AbbKGPUk (ORCPT ); Sat, 7 Nov 2015 10:20:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58644 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753464AbbKGPUj (ORCPT ); Sat, 7 Nov 2015 10:20:39 -0500 Date: Sat, 7 Nov 2015 10:20:38 -0500 (EST) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Sami Tolvanen cc: device-mapper development , Will Drewry , Kees Cook , Mike Snitzer , Mandeep Baines , linux-kernel@vger.kernel.org, Mark Salyzyn Subject: Re: [dm-devel] [PATCH 0/4] dm verity: add support for error correction In-Reply-To: <20151106202750.GA11849@google.com> Message-ID: References: <1446688954-29589-1-git-send-email-samitolvanen@google.com> <563B066C.6050202@redhat.com> <20151106190634.GA2813@google.com> <563CFD6F.4040009@redhat.com> <20151106202750.GA11849@google.com> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1006 Lines: 27 On Fri, 6 Nov 2015, Sami Tolvanen wrote: > On Fri, Nov 06, 2015 at 08:20:15PM +0100, Zdenek Kabelac wrote: > > i.e. you have 1G of space - you want to give 250MB as 'redundancy' - > > so create 4 partition.... > > We cannot afford to set aside 25% of read-only partition space for You can have 20 raid5 legs (with as big chunksizes as possible - so that sequential accesses are really sequential when they hit the flash device), and that means setting aside only 5%. Or even more legs. Mikulas > redundancy on mobile devices, and would rather not impact performance > any more than dm-verity already does. With error correction we have > 0.8% space overhead in our use case and no performance degradation if > the partition is not corrupted. > > Sami -- 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/