Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 31 Jul 2001 19:45:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 31 Jul 2001 19:44:49 -0400 Received: from weta.f00f.org ([203.167.249.89]:21390 "HELO weta.f00f.org") by vger.kernel.org with SMTP id ; Tue, 31 Jul 2001 19:44:32 -0400 Date: Wed, 1 Aug 2001 11:45:13 +1200 From: Chris Wedgwood To: Dan Hollis Cc: Jussi Laako , linux-kernel@vger.kernel.org Subject: Re: ReiserFS / 2.4.6 / Data Corruption Message-ID: <20010801114513.B8839@weta.f00f.org> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.18i X-No-Archive: Yes Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Original-Recipient: rfc822;linux-kernel-outgoing On Tue, Jul 31, 2001 at 03:32:39PM -0700, Dan Hollis wrote: How about an idea I proposed a while back, 'integrity loopback'? A loopback device which writes a CRC with each block and checks the CRC when read back. So if you have a flaky DMA controller, bad cables, etc you will know instantly. It would at least help catch the 'silent corruption' cases. It still doesn't help with block-reordering, the fs needs some way to communication write-barriers or relative block write ordering to the lower-levels. To implement the device, I would hack loopback to take no only the loopback file, but also another 'checksum' file of 160-bits or whatever for each 4096 (or whatever) block. This file might initially be of zero-length, in which case the bind is responsible for checksumming the blocks and writing the checksums out on attach. I say 160-bits (or whatever) so you can use something like SHA1 for the checksums, this way you can use a small application to resync the entire fs at the block level over a network without having to read every block (ie. you compared checksums and then xmit the blocks). The latter is something I needed a while ago. --cw - 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/