Return-Path: linux-nfs-owner@vger.kernel.org Received: from mailgw1.uni-kl.de ([131.246.120.220]:53136 "EHLO mailgw1.uni-kl.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753365Ab2AaTWg (ORCPT ); Tue, 31 Jan 2012 14:22:36 -0500 Message-ID: <4F283F7A.4020905@itwm.fraunhofer.de> Date: Tue, 31 Jan 2012 20:22:34 +0100 From: Bernd Schubert MIME-Version: 1.0 To: "Martin K. Petersen" CC: Chuck Lever , lsf-pc@lists.linux-foundation.org, linux-fsdevel , Linux NFS Mailing List , linux-scsi@vger.kernel.org, Sven Breuner Subject: Re: [LSF/MM TOPIC] end-to-end data and metadata corruption detection References: <38C050B3-2AAD-4767-9A25-02C33627E427@oracle.com> <4F2147BA.6030607@itwm.fraunhofer.de> <4F217F0C.6030105@itwm.fraunhofer.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: On 01/31/2012 03:10 AM, Martin K. Petersen wrote: >>>>>> "Bernd" == Bernd Schubert writes: > > Bernd> Hmm, direct IO would mean we could not use the page cache. As we > Bernd> are using it, that would not really suit us. libaio then might be > Bernd> another option then. > > Bernd> What kind of help do you exactly need? > > As far as libaio is concerned I had a PoC working a few years ago. I'll > be happy to revive it if people are actually interested. So a real world > use case would be a great help... I guess it would be useful for us, although right now data integrity is not on our todo list for the next couple of months. Unless other people would be interested in it right now, can we postpone for some time? > > But James is right that buffered I/O is much more challenging than > direct I/O. And all the use cases we have had have involved databases > and business apps that were doing direct I/O anyway. > I guess we should talk to developers of other parallel file systems and see what they think about it. I think cephfs already uses data integrity provided by btrfs, although I'm not entirely sure and need to check the code. As I said before, Lustre does network checksums already and *might* be interested. Cheers, Bernd