From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:45950 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752009AbbIRAfD (ORCPT ); Thu, 17 Sep 2015 20:35:03 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1Zcjdk-0007Ds-Av for linux-btrfs@vger.kernel.org; Fri, 18 Sep 2015 02:35:00 +0200 Received: from ip98-167-165-199.ph.ph.cox.net ([98.167.165.199]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 18 Sep 2015 02:35:00 +0200 Received: from 1i5t5.duncan by ip98-167-165-199.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 18 Sep 2015 02:35:00 +0200 To: linux-btrfs@vger.kernel.org From: Duncan <1i5t5.duncan@cox.net> Subject: Re: FYIO: A rant about btrfs Date: Fri, 18 Sep 2015 00:34:54 +0000 (UTC) Message-ID: References: <20150916144355.GA1285@invalid> <55F988A6.8070109@gmail.com> <55F9B357.4070505@gmail.com> <54A9EC91-FDFD-44A8-97B9-7347A89FA415@up4.com> <20150916220856.GA23830@hungrycats.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Zygo Blaxell posted on Wed, 16 Sep 2015 18:08:56 -0400 as excerpted: > On Wed, Sep 16, 2015 at 03:04:38PM -0400, Vincent Olivier wrote: >> >> OK fine. Let it be clearer then (on the Btrfs wiki): nobarrier is an >> absolute no go. Case closed. > > Sometimes it is useful to make an ephemeral filesystem, i.e. a btrfs on > a dm-crypt device with a random key that is not stored. This > configuration intentionally and completely destroys the entire > filesystem, and all data on it, in the event of a power failure. It's > useful for things like temporary table storage, where ramfs is too > small, swap-backed tmpfs is too slow, and/or there is a requirement that > the data not be persisted across reboots. > > In other words, nobarrier is for a little better performance when you > already want to _intentionally_ destroy your filesystem on power > failure. Very good explanation of why it's useful to have such an otherwise destructive mount option even available in the first place. Thanks! =:^) -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman