From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753747AbaDWCSj (ORCPT ); Tue, 22 Apr 2014 22:18:39 -0400 Received: from ipmail05.adl6.internode.on.net ([150.101.137.143]:10383 "EHLO ipmail05.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751547AbaDWCSh (ORCPT ); Tue, 22 Apr 2014 22:18:37 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Aq9xAKUiV1N5LEcvPGdsb2JhbABYgwaIbqMFmWeBExcDAQEBATg1giUBAQQBOhwjBQsIAxgJJQ8FJQMHGhOIOQfPQxcWjVwiQgeEOASYb5RFgVErgSwCHg Date: Wed, 23 Apr 2014 12:18:35 +1000 From: Dave Chinner To: Speedy Milan Cc: linux-kernel@vger.kernel.org, Ivan Pantovic , xfs@oss.sgi.com Subject: Re: rm -f * on large files very slow on XFS + MD RAID 6 volume of 15x 4TB of HDDs (52TB) Message-ID: <20140423021835.GI15995@dastard> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [cc xfs@oss.sgi.com] On Mon, Apr 21, 2014 at 10:58:53PM +0200, Speedy Milan wrote: > I want to report very slow deletion of 24 50GB files (in total 12 TB), > all present in the same folder. total = 1.2TB? > OS is CentOS 6.4, with upgraded kernel 3.13.1. > > The hardware is a Supermicro server with 15x 4TB WD Se drives in MD > RAID 6, totalling 52TB of free space. > > XFS is formated directly on the RAID volume, without LVM layers. > > Deletion was done with rm -f * command, and it took upwards of 1 hour > to delete the files. > > File system was filled completely prior to deletion. Oh, that's bad. it's likely you fragmented the files into millions of extents? > rm was mostly waiting (D state), probably for kworker threads, and No, waiting for IO. > iostat was showing big HDD utilization numbers and very low throughput > so it looked like a random HDD workload was in effect. Yup, smells like file fragmentation. Non-fragmented 50GB files should be removed in a few milliseconds. but if you've badly fragmented the files, there could be 10 million extents in a 50GB file. A few milliseconds per extent removal gives you.... Cheers, Dave. -- Dave Chinner david@fromorbit.com