From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Tso Subject: Re: Does \"32.1% non-contigunous\" mean severely fragmented? Date: Fri, 19 Oct 2007 14:52:22 -0400 Message-ID: <20071019185222.GB751@thunk.org> References: <200710190149.l9J1n3Ti083212@www262.sakura.ne.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org To: Tetsuo Handa Return-path: Received: from THUNK.ORG ([69.25.196.29]:46449 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763044AbXJSSwn (ORCPT ); Fri, 19 Oct 2007 14:52:43 -0400 Content-Disposition: inline In-Reply-To: <200710190149.l9J1n3Ti083212@www262.sakura.ne.jp> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Fri, Oct 19, 2007 at 10:49:03AM +0900, Tetsuo Handa wrote: > /data/VMware: 349/19546112 files (32.1% non-contiguous), 31019203/39072080 blocks > > Does non-contiguous mean fragmented? > If so, where is ext3defrag? Not necessarily; it just means that 32% of your files have at least one discontinuity. Given the ext3 layout, by definition every 128 megs there will be a discontinuity because of the metadata at the beginning of every single block group. You have a small number of files on your system (349) occupying an average of 348 megabytes. So it's not at all surprising that the contiguous percentage is 32%. The recent Flex BG feature that was recently pulled into 2.6.23-git14 for ext4 is desgined to avoid this issue, but a seek every 128 megs is for most workloads not a big deal and will hopefully not cause you any problems. - Ted