From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id n5J9Zxbh058103 for ; Fri, 19 Jun 2009 04:35:59 -0500 Received: from firestarter.dermichi.com (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id D03C330A52C for ; Fri, 19 Jun 2009 02:36:23 -0700 (PDT) Received: from firestarter.dermichi.com (firestarter.dermichi.com [83.64.48.195]) by cuda.sgi.com with ESMTP id zW7PtinjoEjVt9Vc for ; Fri, 19 Jun 2009 02:36:23 -0700 (PDT) Received: from cerberus.net4you.net ([194.177.153.130] helo=[192.168.200.110]) by firestarter.dermichi.com with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.69) (envelope-from ) id 1MHaWE-0005cO-Nr for xfs@oss.sgi.com; Fri, 19 Jun 2009 11:36:22 +0200 Message-ID: <4A3B5C14.9070101@dermichi.com> Date: Fri, 19 Jun 2009 11:36:20 +0200 From: Michael Weissenbacher MIME-Version: 1.0 Subject: XFS and atime update strangeness List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com Hi XFS-List! As i have been playing around with atime settings recently, i noticed that XFS handles atime updates very differently than other filesystems (at least different than ext2/3/4 and reiserfs). In fact it does not record atime changes permanently, it seems that atimes are only stored in the inode cache. I was testing this on a Gentoo Box with kernel 2.6.28-gentoo-r5 and 2.6.30 Vanilla. How to reproduce? invincible usr # ls -lu portage/header.txt -rw-r--r-- 1 root root 121 2009-06-18 22:06 portage/header.txt invincible usr # date Fri Jun 19 11:24:53 CEST 2009 invincible usr # cat portage/header.txt > /dev/null invincible usr # ls -lu portage/header.txt -rw-r--r-- 1 root root 121 2009-06-19 11:24 portage/header.txt invincible usr # umount portage && mount portage invincible usr # ls -lu portage/header.txt -rw-r--r-- 1 root root 121 2009-06-18 22:06 portage/header.txt So after umount && mount the atime instantly went back to the old value. I can also sometimes reproduce it by doing "sync && echo 3 > /proc/sys/vm/drop_caches". If i wait for a day the atime also reverts back. Rebooting the machine has the same effect. I haven't found anything in the official documentation stating this. The only reference i found was a while back in the mailing list: http://oss.sgi.com/archives/xfs/2007-10/msg00171.html I think there should be at least some information about this behavior in the official docs and the FAQ. IMO This feature/bug of XFS also collides with the recent change to make relatime the default in kernel 2.6.30. Is there any way to enable permanent atime updates in case someone wants them? Michael _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs