From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932125AbWGCVH5 (ORCPT ); Mon, 3 Jul 2006 17:07:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932126AbWGCVH5 (ORCPT ); Mon, 3 Jul 2006 17:07:57 -0400 Received: from ns1.soleranetworks.com ([70.103.108.67]:11245 "EHLO ns1.soleranetworks.com") by vger.kernel.org with ESMTP id S932125AbWGCVH4 (ORCPT ); Mon, 3 Jul 2006 17:07:56 -0400 Message-ID: <44A9904F.7060207@wolfmountaingroup.com> Date: Mon, 03 Jul 2006 15:46:55 -0600 From: "Jeff V. Merkey" User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040510 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Arjan van de Ven CC: Tomasz Torcz , Helge Hafting , Thomas Glanzmann , "Theodore Ts'o" , LKML Subject: Re: ext4 features References: <20060701163301.GB24570@cip.informatik.uni-erlangen.de> <20060701170729.GB8763@irc.pl> <20060701174716.GC24570@cip.informatik.uni-erlangen.de> <20060701181702.GC8763@irc.pl> <20060703202219.GA9707@aitel.hist.no> <20060703205523.GA17122@irc.pl> <1151960503.3108.55.camel@laptopd505.fenrus.org> In-Reply-To: <1151960503.3108.55.camel@laptopd505.fenrus.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Arjan van de Ven wrote: >> ZFS was already called ,,blatant layering violation''. ;) >>Yes,that what RAID is for. And if we want checksums in filesystem, >>that's the best way to utilise them. >> >> > > >Hi, > >checksums have a very different purpose than raid. > >checksums are great at detecting corruption. And yes, corruption can >happen even if you have raid, for many many reasons. Detecting means >knowing when to not trust something, when to go for the backup tapes... > >raid is great for protecting against individual disks or sectors going >bad. But raid, especially high performance implementations, do not >checksum data or detect corruptions. > >They're different purpose with almost zero overlap in purpose or even >goal... > >- >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/ > > > Add a salvagable file system to ext4, i.e. when a file is deleted, you just rename it and move it to a directory called DELETED.SAV and recycle the files as people allocate new ones. Easy to do (internal "mv" of file to another directory) and modification of the allocation bitmaps. Very simple and will pay off big. If you need help designing it, just ask me. Jeff