Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757713AbXHEH2k (ORCPT ); Sun, 5 Aug 2007 03:28:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753904AbXHEH2a (ORCPT ); Sun, 5 Aug 2007 03:28:30 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:38613 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753631AbXHEH23 (ORCPT ); Sun, 5 Aug 2007 03:28:29 -0400 Date: Sun, 5 Aug 2007 09:28:05 +0200 From: Ingo Molnar To: Alan Cox Cc: Claudio Martins , Jeff Garzik , =?iso-8859-1?Q?J=F6rn?= Engel , Linus Torvalds , Peter Zijlstra , linux-mm@kvack.org, Linux Kernel Mailing List , miklos@szeredi.hu, akpm@linux-foundation.org, neilb@suse.de, dgc@sgi.com, tomoki.sekiyama.qu@hitachi.com, nikita@clusterfs.com, trond.myklebust@fys.uio.no, yingchao.zhou@gmail.com, richard@rsk.demon.co.uk, david@lang.hm Subject: Re: [PATCH 00/23] per device dirty throttling -v8 Message-ID: <20070805072805.GB4414@elte.hu> References: <20070803123712.987126000@chello.nl> <46B4E161.9080100@garzik.org> <20070804224706.617500a0@the-village.bc.nu> <200708050051.40758.ctpm@ist.utl.pt> <20070805014926.400d0608@the-village.bc.nu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070805014926.400d0608@the-village.bc.nu> User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: 1.0 X-ELTE-SpamLevel: s X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=1.0 required=5.9 tests=BAYES_50 autolearn=no SpamAssassin version=3.0.3 1.0 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1230 Lines: 27 * Alan Cox wrote: > > Can you give examples of backup solutions that rely on atime being > > updated? I can understand backup tools using mtime/ctime for > > incremental backups (like tar + Amanda, etc), but I'm having trouble > > figuring out why someone would want to use atime for that. > > HSM is the usual one, and to a large extent probably why Unix > originally had atime. Basically migrating less used files away so as > to keep the system disks tidy. atime is used as a _hint_, at most and HSM sure works just fine on an atime-incapable filesystem too. So it's the same deal as "add user_xattr mount option to the filesystem to make Beagle index faster". It's now: "if you use HSM storage add the atime mount option to make it slightly more intelligent. Expect huge IO slowdowns though." The only remotely valid compatibility argument would be Mutt - but even that handles it just fine. (we broke way more software via noexec) Ingo - 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/