From: Eric Sandeen Subject: Re: Do we need dump for ext4? Date: Tue, 02 Sep 2008 10:52:03 -0500 Message-ID: <48BD6123.9090406@redhat.com> References: <48B6BD02.3080307@redhat.com> <48B7ED40.6020508@redhat.com> <20080831024300.GB3392@webber.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: ext4 development , Ric Wheeler To: Andreas Dilger Return-path: Received: from mx2.redhat.com ([66.187.237.31]:37516 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751113AbYIBPxl (ORCPT ); Tue, 2 Sep 2008 11:53:41 -0400 In-Reply-To: <20080831024300.GB3392@webber.adilger.int> Sender: linux-ext4-owner@vger.kernel.org List-ID: Andreas Dilger wrote: > On Aug 29, 2008 07:36 -0500, Eric Sandeen wrote: >> at Ric & hch's request here is tar on the other fs's as well, re-sorted >> by level 0 dump time. I put acp into the mix as well. >> >> Oh, and this time I remembered to set the elevator to something sane >> (noop) for this storage, oops (was cfq last time) >> >> Also, this time the dup/tar/acp was written to /dev/null rather than >> another filesystem. Interesting how routing to /dev/null alone changed >> the ranking quite a bit. > > Note that tar has a (questionable) optimization when writing to /dev/null. > It will NOT open the file or read the data, and just do the filename > traversal to generate the file list and total file size. It does this by > comparing the output file to "/dev/null": Ah, crud. -Eric