From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Tso Subject: Re: Does "32.1% non-contiguous" mean severely fragmented? Date: Tue, 23 Oct 2007 08:34:16 -0400 Message-ID: <20071023123416.GH27132@thunk.org> References: <20071019185222.GB751@thunk.org> <200710201239.BIF34800.OOJQFLMHFVtFOS@I-love.SAKURA.ne.jp> <20071020131719.GA8860@thunk.org> <200710222058.FBC09363.tFVJOOSFLHFQMO@I-love.SAKURA.ne.jp> <20071022130245.GC29220@thunk.org> <200710231938.BAI69744.FHLOMJOFFVtSOQ@I-love.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]:42333 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751684AbXJWMe1 (ORCPT ); Tue, 23 Oct 2007 08:34:27 -0400 Content-Disposition: inline In-Reply-To: <200710231938.BAI69744.FHLOMJOFFVtSOQ@I-love.SAKURA.ne.jp> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, Oct 23, 2007 at 07:38:20PM +0900, Tetsuo Handa wrote: > > Are you sure the file isn't getting written by some background tasks > > that you weren't aware of? This seems very strange; what > > virtualization software are you using? VMware, Xen, KVM? > I'm using VMware Workstation 6.0.0 build 45731 for x86_64. > It seems that there were some background tasks that delays writing. > I tried the following sequence, "sync" didn't affect. Or it may be that it takes a while to do a controlled shutdown. One potential reason for the vmem file being very badly fragmented is that it might not be getting written in sequential order. If the writer is writing the file in random order, then unless you have a filesystem which can do delayed allocations, the blocks will get allocated in the other that they are first written, and if the writer is seeking to random locations to do the write, that's one way that you can end up with a very badly fragmented file. Regards, - Ted