From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f67.google.com ([209.85.214.67]:33833 "EHLO mail-it0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751529AbdEHQlR (ORCPT ); Mon, 8 May 2017 12:41:17 -0400 Received: by mail-it0-f67.google.com with SMTP id c26so7895660itd.1 for ; Mon, 08 May 2017 09:41:17 -0700 (PDT) Subject: Re: BTRFS converted from EXT4 becomes read-only after reboot To: Sean Greenslade , Sanidhya Solanki , Alexandru Guzu References: <706980A2-DC62-45AA-B169-8A9D6E474D87@seangreenslade.com> <20170508112617.7e33bed6@ad> Cc: Btrfs BTRFS , Qu Wenruo From: "Austin S. Hemmelgarn" Message-ID: <4aedf23f-2bc4-ce18-d5b0-13fa51496feb@gmail.com> Date: Mon, 8 May 2017 12:41:11 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2017-05-08 12:22, Sean Greenslade wrote: > On May 8, 2017 11:28:42 AM EDT, Sanidhya Solanki wrote: >> On Mon, 8 May 2017 10:16:44 -0400 >> Alexandru Guzu wrote: >> >>> Sean, how would you approach the copy of the data back and forth if >>> the OS is on it? Would a Send-receive and then back work? >> >> You could use a Live-USB and then just dd it to remote or attached >> storage, if >> you want to be absolutely sure the data is not affected. > > I would not suggest either of those. Send / receive might work, but since we don't know the source of the problem, it risks transferring the problem. DD would not solve the problem at all, since we're trying to rebuild the partition, not clone it. Send/receive is not likely to transfer the problem unless it has something to do with how things are reflinked. Receive operates by recreating the sent subvolume from userspace using regular commands and the clone ioctls, so it won't replicate any low-level structural issues in the filesystem unless they directly involve the way extents are being shared (or are a side effect of that). On top of that, if there is an issue on the sending side, send itself will probably not send that data, so it's actually only marginally more dangerous than using something like rsync to copy the data.