From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from caibbdcaaaaf.dreamhost.com ([208.113.200.5]:50583 "EHLO homiemail-a51.g.dreamhost.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754602Ab3GVDhi (ORCPT ); Sun, 21 Jul 2013 23:37:38 -0400 From: Shridhar Daithankar To: george@chinilu.com Cc: Duncan <1i5t5.duncan@cox.net>, linux-btrfs@vger.kernel.org Subject: Re: autodefrag by default, was: Lots of harddrive chatter Date: Mon, 22 Jul 2013 09:07:35 +0530 Message-ID: <5436903.bmHYcuMpfJ@bheem> In-Reply-To: <51EC7249.3010005@chinilu.com> References: <51EC7249.3010005@chinilu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Sunday, July 21, 2013 04:44:09 PM George Mitchell wrote: > Unless auto-defrag can work around the > in-use file issue, that could be a problem since some heavily used > system files are open virtually all the time the system is up and > running. Has this issue been investigated and if so are there any > system files that don't get defragmented that matter? Or is this a > non-issue in that any constantly in use system files don't really matter > anyway? That is really the only question I have before moving away from > my current offline approach to the auto-defrag mount option for system > filesystems (/, /boot, /usr, /opt, /var, etc). AFAIK, defragmentation is proportional to amount of writes to a file or direcotries. system files typically are installed once and never rewritten in place, so they should not be much fragmented to begin with. now their directory objects, is a different story and so is things like systemd journal, log files, or database files. -- Regards Shridhar