From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-32-i2.italiaonline.it ([212.48.25.202]:41396 "EHLO smtp-32.italiaonline.it" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753329AbaLGXAI (ORCPT ); Sun, 7 Dec 2014 18:00:08 -0500 Message-ID: <5484DC3C.7040409@inwind.it> Date: Mon, 08 Dec 2014 00:01:16 +0100 From: Goffredo Baroncelli Reply-To: kreijack@inwind.it MIME-Version: 1.0 To: ashford@whisperpc.com CC: Shriramana Sharma , Martin Steigerwald , linux-btrfs Subject: Re: Why is the actual disk usage of btrfs considered unknowable? References: <44320137.fRRuR6EFMP@merkaba> <5484A83A.5090109@inwind.it> <6554b2b132dd3f9803bcf8c10f11a156.squirrel@webmail.wanet.net> In-Reply-To: <6554b2b132dd3f9803bcf8c10f11a156.squirrel@webmail.wanet.net> Content-Type: text/plain; charset=windows-1252 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 12/07/2014 09:32 PM, ashford@whisperpc.com wrote: >> In conclusion, the disk usage is well known; which is unknown is >> > the space that is available to the user (who is uninterested to >> > all the details inside a filesystem). The best that is doable >> > is an estimation like the above one. > I disagree. My experiences with other file-systems, including ZFS, show > that the most common solution is to just deliver to the user the actual > amount of unused disk space. Anything else changes this known value into > a guess or prediction. So in case you have a raid1 filesystem on two disks; each disk has 300GB free; which is the free space that you expected: 300GB or 600GB and why ? > > Peter Ashford BR G.Baroncelli > > -- gpg @keyserver.linux.it: Goffredo Baroncelli Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5