From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 343D8139B2A for ; Fri, 18 Sep 2015 21:58:43 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 3BE1521C01A; Fri, 18 Sep 2015 21:58:35 +0000 (UTC) Received: from mail-wi0-f175.google.com (mail-wi0-f175.google.com [209.85.212.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id EE517E0894 for ; Fri, 18 Sep 2015 21:58:33 +0000 (UTC) Received: by wicfx3 with SMTP id fx3so46463075wic.0 for ; Fri, 18 Sep 2015 14:58:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:reply-to:to:subject:date:user-agent:references:in-reply-to :mime-version:content-type:content-transfer-encoding:message-id; bh=Nnpemmp7pQgrPAY3S9N2BCRZ+0VHDz3/E8bAjVIF8qc=; b=uWscPEjHZU5ZfLWeEDZHxtdjmhZoQpqJfflTZwqcNbzQEHw4jzwJhYjLAbbpNNtq3S aS5JVxXMy91FR+W+bBMtuyqc2GuzkPJxBKzDSlcbbaAF+tRpu7heEXMog8v8ex0xIQMz F1lo9bQJjRUQ6YvoXXSVCQVDQrhEtr992USGrBLGYHLCeWZ+TXjkpstTsNdk1XEHCy7a vT17dPVdsY5Zt1PIaJC6sDOE3GbGFuWB1wmIrMitQW4CRQrzrk9swa/xx8F/0s8nDtIg hQ7kYJnNkgcd+Ly5FXiile02ppG80IrIh4oDNYZOmLlBOlj13akwuluJ+cqq7ouVLrNd u6UA== X-Received: by 10.180.211.8 with SMTP id my8mr370571wic.21.1442613512764; Fri, 18 Sep 2015 14:58:32 -0700 (PDT) Received: from dell_xps.localnet (230.3.169.217.in-addr.arpa. [217.169.3.230]) by smtp.gmail.com with ESMTPSA id jw9sm10880206wjb.28.2015.09.18.14.58.31 for (version=TLS1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 18 Sep 2015 14:58:32 -0700 (PDT) From: Mick To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] BTRFS problem? [WAS Quick check on net-print/hplip-3.14.10] Date: Fri, 18 Sep 2015 22:58:12 +0100 User-Agent: KMail/1.13.7 (Linux/4.0.5-gentoo; KDE/4.14.8; x86_64; ; ) References: <201509162222.40567.michaelkintzios@gmail.com> <201509181920.08912.michaelkintzios@gmail.com> In-Reply-To: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1635641.I9PO9t1Qk6"; protocol="application/pgp-signature"; micalg=pgp-sha256 Content-Transfer-Encoding: 7bit Message-Id: <201509182258.28664.michaelkintzios@gmail.com> X-Archives-Salt: ef04e9e5-a52f-417d-a4fe-1bbed4eed776 X-Archives-Hash: 2f9f3dbd40887aab912b85b7e52461ef --nextPart1635641.I9PO9t1Qk6 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Friday 18 Sep 2015 19:30:49 Rich Freeman wrote: > On Fri, Sep 18, 2015 at 2:19 PM, Mick wrote: > > On Friday 18 Sep 2015 19:15:50 Rich Freeman wrote: > >> On Fri, Sep 18, 2015 at 1:56 PM, Mick wrot= e: > >> > On Friday 18 Sep 2015 17:16:54 Marc Joliet wrote: > >> >> On Friday 18 September 2015 10:31:01 Mick wrote: > >> >> >A couple of months ago the akonadi DB went sideways and kmail play= ed > >> >> >up as a result. Again I was suspicious of btrfs, but neither the > >> >> >logs nor fsck showed up anything. > >> >>=20 > >> >> I take it "btrfs scrub" didn't turn up anything, or is that what you > >> >> meant by fsck? > >> >=20 > >> > Am I supposed to run scrub with I do not have a RAID running? I > >> > thought scrub was meant for comparing checksums between mirrored fs - > >> > have I got this wrong? > >>=20 > >> You can actually run scrub on a non-raid btrfs setup. Btrfs will > >> report any errors that it detects (using the checksumming in the > >> filesystem), but it would not be able to fix errors unless you have it > >> storing redundant data somewhere (even on non-raid it still stores > >> redundant metadata by default, and you can choose to do this with data > >> as well which protects against block-level failures but not disk-level > >> failures, obviously). > >>=20 > >> However, you'd have gotten the same errors in dmesg just trying to > >> read the files - btrfs checks the checksum on all file read > >> operations. That is a big part of the value of both btrfs and zfs. > >=20 > > Ah! V interesting ... can I run scrub with mounted partitions, or do I > > have to do it from a LiveCD? >=20 > I didn't check, but I suspect you can only run scrub on a mounted > partition. I also suspect that fsck probably has an option to do > something equivalent offline. >=20 > You do get the error-detection anyway just by reading files, and if > you just ran find on your filesystem and catted every file you have to > /dev/null that would actually accomplish the same thing as long as > you're not in a redundant mode (simply reading all the files doesn't > guarantee that all copies of each file are checked). >=20 > The main reason for doing a scrub is to detect latent issues, and if > you have redundancy that means you can auto-correct them today, rather > than discovering them a month from now when the drive containing the > only good copy fails. Even if you don't have redundancy maybe you > rotate your backups every 30 days and detecting the error might mean > having the ability to go back and restore a good copy of the file > before it is completely replaced with bad copies. Thank you Rich, I ran 'btrfs scrub start /" and it found zero problems. dm= esg=20 and syslog clean too.=20 =2D-=20 Regards, Mick --nextPart1635641.I9PO9t1Qk6 Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABCAAGBQJV/IkEAAoJELAdA+zwE4Yewa4IAKc7EPkYiHnwy1oA/vIFrOix 9YXicQ/Kq1paFn6C+EHgHbdbcpdNhUSLkPbt0GpUGSfA7BHl7pmq3IHo08gfAEDj y1OJWRrz49Ph62BDc4cg7yzegVBjUL6eFn/o68DtWiuz2lGUEQqcNolq3zcAtuqr YDVxmqn3lBtlArm1aukWFJR5gkHwcizI0Yk+zQKA339bL14g/KsnYmr0xy9XwAgC EpDSoKyHeN+edhsbvyoJbOF77mZyptTick/uEjSvz2qhOt6XQggdU6p9jfwSZXEI NLIEQkk/cxyJN32Iw2ukbOvKhZEjYoKO7tSHRUr70nrvuY0JSHR3U8tWP4UcqMI= =Z/Ep -----END PGP SIGNATURE----- --nextPart1635641.I9PO9t1Qk6--