From: "Ricardo M. Correia" Subject: Re: Mentor for a GSoC application wanted (Online ext2/3 filesystem checker) Date: Mon, 21 Apr 2008 19:27:21 +0100 Message-ID: <1208802441.14123.39.camel@localhost> References: <20080419012952.GE25797@mit.edu> <20080419185603.GA30449@mit.edu> <480A42F6.2030005@redhat.com> <20080419220432.GB30449@mit.edu> <87iqyc85q7.fsf@basil.nowhere.org> <20080420234241.GB23292@shareable.org> <20080421080111.GD14446@one.firstfloor.org> <1208798974.14123.28.camel@localhost> <480CD18F.7000108@firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7BIT Cc: Theodore Tso , Eric Sandeen , Alexey Zaytsev , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, Rik van Riel To: Andi Kleen Return-path: Received: from gmp-eb-inf-1.sun.com ([192.18.6.21]:58609 "EHLO gmp-eb-inf-1.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755129AbYDUS1Y (ORCPT ); Mon, 21 Apr 2008 14:27:24 -0400 In-reply-to: <480CD18F.7000108@firstfloor.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Seg, 2008-04-21 at 19:40 +0200, Andi Kleen wrote: > > Is there a reason why this isn't being done other than performance? > > One reason against it is that in many (but not all) setups to guarantee > reaching the platter you have to disable the write cache, and at least > for consumer level hard disks disk vendors generally do not recommend > doing this because it significantly lowers the MTBF of the disk. I understand that, but if the disk/storage doesn't support flushing the cache, I would expect fsync() to return EIO or ENOTSUP, I wouldn't expect it to ignore my request and risk losing data without my knowledge.. I know fsync() also flushes dirty buffers, but IMHO even if it flushes the buffers it'd be better to return an error if a full sync wasn't being done rather than returning success and misleading the application. Anyway, sorry if this has been discussed before, I should take a look at the archives.. Thanks, Ricardo -- Ricardo Manuel Correia Lustre Engineering Sun Microsystems, Inc. Portugal Phone +351.214134023 / x58723 Mobile +351.912590825 Email Ricardo.M.Correia@Sun.COM