From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:47905 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752894AbcCUJzg (ORCPT ); Mon, 21 Mar 2016 05:55:36 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1ahwYg-0001AA-2u for linux-btrfs@vger.kernel.org; Mon, 21 Mar 2016 10:55:34 +0100 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 ; Mon, 21 Mar 2016 10:55:34 +0100 Received: from 1i5t5.duncan by ip98-167-165-199.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 21 Mar 2016 10:55:34 +0100 To: linux-btrfs@vger.kernel.org From: Duncan <1i5t5.duncan@cox.net> Subject: Re: overlay file to test btrfs repairs Date: Mon, 21 Mar 2016 09:55:23 +0000 (UTC) Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Chris Murphy posted on Sun, 20 Mar 2016 21:43:52 -0600 as excerpted: > Hi folks, > > So I just ran into this: > https://raid.wiki.kernel.org/index.php/ Recovering_a_failed_software_RAID#Making_the_harddisks_read- only_using_an_overlay_file [That's a single link, wrapped by my client.] > This is a device mapper overlay file - not overlayfs. > > For the repairs that are sometimes uncertain what's next, maybe this is > a viable option to avoid changing the file system? I'm thinking > chunk-recover might take up too much space, I'm not sure how that one > works, if chunks are just being read or if they have to be rewritten or > if it's just the chunk tree? But for 'btrfs check' and 'btrfs rescue > super-recover/zero-log' there should be very little being written so the > overlay idea might be a good step? > > Opinions? That's a creative and potentially quite useful possible solution to an often hairy problem. Thanks for bringing it up. =:^) Provided Hugo and the devs don't find major fault with the idea, linking that from appropriate locations (as a possible solution in the Problem FAQ is the first one that occurs to me) in the btrfs wiki could be quite useful, to many. -- 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