From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out2.mail.ruhr-uni-bochum.de ([134.147.42.229]:55549 "EHLO out2.mail.ruhr-uni-bochum.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752017AbeENUK4 (ORCPT ); Mon, 14 May 2018 16:10:56 -0400 Received: from mx2.mail.ruhr-uni-bochum.de (localhost [127.0.0.1]) by out2.mail.ruhr-uni-bochum.de (Postfix mo-ext) with ESMTP id 40lBSf2N9Cz4y5M for ; Mon, 14 May 2018 22:02:42 +0200 (CEST) Received: from out2.mail.ruhr-uni-bochum.de (localhost [127.0.0.1]) by mx2.mail.ruhr-uni-bochum.de (Postfix idis) with ESMTP id 40lBSf1nmTz4y67 for ; Mon, 14 May 2018 22:02:42 +0200 (CEST) Received: from mail1.mail.ruhr-uni-bochum.de (mail1.mail.ruhr-uni-bochum.de [134.147.42.227]) by out2.mail.ruhr-uni-bochum.de (Postfix mi-int) with ESMTP id 40lBSf1PRxz4y5M for ; Mon, 14 May 2018 22:02:42 +0200 (CEST) Received: from webmail.ruhr-uni-bochum.de (vmrz0224.rz.ruhr-uni-bochum.de [134.147.64.15]) by mail1.mail.ruhr-uni-bochum.de (Postfix) with ESMTPSA id 40lBSd6vcBzyXK for ; Mon, 14 May 2018 22:02:41 +0200 (CEST) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 14 May 2018 22:02:41 +0200 From: Tarik Ceylan Subject: How to reliably measure fs usage with reflinks enabled? Message-ID: <5398ddaf2b876c3563bc1c2927bfe1b9@ruhr-uni-bochum.de> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: linux-xfs@vger.kernel.org How can one reliably measure filesystem usage on partitions that were compiled with -m reflink=1 ? Here are some numbers i am measuring with df -h (on different partitions holding the same data): 7.7G of 36G (-b size=512 -m crc=0 ) 8.6G of 36G (-b size=4096 -m crc=1 ) 11G of 36G (-b size=1024 -m crc=1,reflink=1,rmapbt=1 -i sparse=1 ) 32G of 864G (-b size=4096 -m crc=1,reflink=1 ) I already ruled out fragmentation as a cause. The data does not contain many duplicates (roughly 200mb could be freed by deduplicating). Since measuring fs usage on btrfs also isn't trivial, i would suspect that there are similar problems happening here. But i could not find any information on how to measure fs usage properly when using xfs with reflinks. Kernel in use is 4.14.40. Tarik Ceylan (I am not subscribed to this list, i'd be grateful if you could CC me in your reply)