From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sun, 5 Aug 2007 09:28:05 +0200 From: Ingo Molnar 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> Sender: owner-linux-mm@kvack.org Return-Path: 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 List-ID: * 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org