From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [RFC] TileFS - a proposal for scalable integrity checking Date: 29 Apr 2007 18:34:59 +0200 Message-ID: References: <20070428220522.GN11166@waste.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org To: Matt Mackall Return-path: Received: from cantor.suse.de ([195.135.220.2]:41792 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756283AbXD2PhU (ORCPT ); Sun, 29 Apr 2007 11:37:20 -0400 In-Reply-To: <20070428220522.GN11166@waste.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Matt Mackall writes: > This is a relatively simple scheme for making a filesystem with > incremental online consistency checks of both data and metadata. > Overhead can be well under 1% disk space and CPU overhead may also be > very small, while greatly improving filesystem integrity. Problem I see is that your scheme doesn't support metadata checksums only. IMHO those are the most interesting because they have the potential to be basically zero cost, unlike full data checksumming. And doing metadata checksums is enough to handle the fsck problem. I'm sure there are many cases where full checksumming makes sense too, but those shouldn't be forced on everybody because it will slow down some important workloads (like O_DIRECT) Metadata checksums would be best just put into the file systems data structures. Essentially every object (inode, extent, directory entry, super block) should have a checksum that can be incrementially updated. -Andi