From: Andreas Dilger Subject: Re: [PATCH] default max mount count to unused Date: Fri, 22 Jan 2010 11:40:41 -0700 Message-ID: <2B15E63C-8EE9-4675-B659-5D1A302334C8@sun.com> References: <4B5785A5.2010505@redhat.com> <20100122012929.GA21263@thunk.org> <4B591D80.6010309@redhat.com> <4B7FFE9D-F110-408D-B432-7D20AEBD4689@sun.com> <4B59DA16.3060906@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; CHARSET=US-ASCII; delsp=yes; format=flowed Content-Transfer-Encoding: 7BIT Cc: Eric Sandeen , tytso@mit.edu, ext4 development , Bill Nottingham To: Ric Wheeler Return-path: Received: from sca-es-mail-2.Sun.COM ([192.18.43.133]:57640 "EHLO sca-es-mail-2.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756147Ab0AVSko (ORCPT ); Fri, 22 Jan 2010 13:40:44 -0500 Received: from fe-sfbay-09.sun.com ([192.18.43.129]) by sca-es-mail-2.sun.com (8.13.7+Sun/8.12.9) with ESMTP id o0MIeiC4003811 for ; Fri, 22 Jan 2010 10:40:44 -0800 (PST) Received: from conversion-daemon.fe-sfbay-09.sun.com by fe-sfbay-09.sun.com (Sun Java(tm) System Messaging Server 7u2-7.04 64bit (built Jul 2 2009)) id <0KWN00H00VL7ZZ00@fe-sfbay-09.sun.com> for linux-ext4@vger.kernel.org; Fri, 22 Jan 2010 10:40:44 -0800 (PST) In-reply-to: <4B59DA16.3060906@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2010-01-22, at 10:02, Ric Wheeler wrote: >> I've thought for quite a while that 20 mounts is too often, but I'm >> reluctant to turn it off completely. I wouldn't object to >> increasing it to 60 or 80. >> >> At one time there was a patch that checked the state of the >> filesystem at mount time and only incremented only 1/5 of the time >> (randomly) if it was unmounted cleanly (not dirty, or not in >> recovery), but every time if it crashed. The reasoning was that >> systems which crashed are more likely to have memory corruption or >> software bugs, and ones that shut down cleanly are less likely to >> have such problems. >> > > I do like the snapshot idea, but also think that we need something > will not introduce random (potentially multi-hour or multi-day) fsck > runs after an otherwise clean reboot. > > If we hit this with a combination of: > > Reboot time: > (1) Try to mount the file system > (1) on mount failure, fsck the failed file system Well, this is essentially what already happens with e2fsck today, though it correctly checks the filesystem for errors _first_, and _then_ mounts the filesystem. Otherwise it isn't possible to fix the filesystem after mount, and mounting a filesystem with errors is a recipe for further corruption and/or a crash/reboot cycle. > While up and running, do a periodic check with the snapshot trick. Yes, this is intended to reset the periodic mount/time counter to avoid the non-error boot-time check. If that is not running correctly then the periodic check would still be done as a fail-safe measure. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.