From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f51.google.com ([74.125.82.51]:36077 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751688AbcAEQeE (ORCPT ); Tue, 5 Jan 2016 11:34:04 -0500 Received: by mail-wm0-f51.google.com with SMTP id l65so29391548wmf.1 for ; Tue, 05 Jan 2016 08:34:02 -0800 (PST) Subject: Re: Purposely using btrfs RAID1 in degraded mode ? To: Alphazo , linux-btrfs@vger.kernel.org References: From: Psalle Message-ID: <568BF078.8060303@gmail.com> Date: Tue, 5 Jan 2016 17:34:00 +0100 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: Hello Alphazo, I am a mere btrfs user, but given the discussions I regularly see here about difficulties with degraded filesystems I wouldn't rely on this (yet?) as a regular work strategy, even if it's supposed to work. If you're familiar with git, perhaps git-annex could be an alternative. -Psalle. On 04/01/16 18:00, Alphazo wrote: > Hello, > > My picture library today lies on an external hard drive that I sync on > a regular basis with a couple of servers and other external drives. > I'm interested by the on-the-fly checksum brought by btrfs and would > like to get your opinion on the following unusual use case that I have > tested: > - Create a btrfs with the two drives with RAID1 > - When at home I can work with the two drives connected so I can enjoy > the self-healing feature if a bit goes mad so I only backup perfect > copies to my backup servers. > - When not at home I only bring one external drive and manually mount > it in degraded mode so I can continue working on my pictures while > still having checksum error detection (but not correction). > - When coming back home I can plug-back the seconde drive and initiate > a scrub or balance to get the second drive duplicated. > > I have tested the above use case with a couple of USB flash drive and > even used btrfs over dm-crypt partitions and it seemed to work fine > but I wanted to get some advices from the community if this is really > a bad practice that should not be used on the long run. Is there any > limitation/risk to read/write to/from a degraded filesystem knowing it > will be re-synced later? > > Thanks > alphazo > > PS: I have also investigated the RAID1 on a single drive with two > partitions but I cannot afford the half capacity resulting from that > approach. > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html