From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ngcobalt08.manitu.net ([217.11.48.108]:60510 "EHLO ngcobalt08.manitu.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751951AbaARAw7 (ORCPT ); Fri, 17 Jan 2014 19:52:59 -0500 Received: from [172.22.99.183] (p4FF1D561.dip0.t-ipconnect.de [79.241.213.97]) (Authenticated sender: jseifert) by ngcobalt08.manitu.net (Postfix) with ESMTPSA id AABC63A801E for ; Sat, 18 Jan 2014 01:53:01 +0100 (CET) Message-ID: <52D9D061.1070100@dergleichrichter.de> Date: Sat, 18 Jan 2014 01:52:49 +0100 From: Justus Seifert MIME-Version: 1.0 To: linux-btrfs@vger.kernel.org Subject: Re: drawbacks of non-ECC RAM References: <1389983615.90027.YahooMailNeo@web172606.mail.ir2.yahoo.com> In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="lk4XmtVCdvckLhwdCcsdUVoOlJh0tOI6R" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --lk4XmtVCdvckLhwdCcsdUVoOlJh0tOI6R Content-Type: multipart/mixed; boundary="------------000109080709080302000708" This is a multi-part message in MIME format. --------------000109080709080302000708 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 18.01.2014 00:18, Duncan wrote: > valleysmail-lol5@yahoo.de posted on Fri, 17 Jan 2014 18:33:35 +0000 as > excerpted: >=20 >> I'd like to know if there are drawbacks in using btrfs with non-ECC RA= M >> instead of using ext4 with non-ECC RAM. I know that some features of >> btrfs may rely on ECC RAM=20 >=20 > Crossed signals somewhere, as that's entirely incorrect. Btrfs does ha= ve=20 > date integrity checksumming as one of its features -- one which I'm usi= ng=20 > here BTW with raid1 mode so there's two copies of everything, on=20 > different devices, in case one goes bad -- but BTRFS IN NO WAY REQUIRES= =20 > ECC RAM. ECC RAM is a hardware solution to a conceptually similar data= =20 > integrity problem in memory to the problem btrfs addresses as filesyste= m=20 > software for non-volatile storage, but the two shouldn't be confused fo= r=20 > each other or conflated at all -- they're entirely separate in practice= ,=20 > and one is hardware while the other is software. To be fair: Both problems are essentially hardware problems where data gets corrupted, but the solutions are different. ECC is only used in systems where the additional cost for the hardware, energy (registered ECC-RAM uses more electricity than register-less non-ECC-RAM), and space (ECC-RAM is physically larger) is less than the cost of recovery in case of soft errors caused by non-ECC-RAM. ECC-RAM does not offer a memory performance advantage. See Wikipedia for more info about registered RAM and ECC-RAM. Raid1 uses more power and space as well, but also adds read performance. So _there are reasons to use Raid1 besides resilience_. > [=E2=80=A6] --------------000109080709080302000708 Content-Type: text/x-vcard; charset=utf-8; name="justus_seifert.vcf" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="justus_seifert.vcf" YmVnaW46dmNhcmQNCmZuOkp1c3R1cyBTZWlmZXJ0DQpuOlNlaWZlcnQ7SnVzdHVzDQphZHI6 Ozs7RHJlc2RlbjtTYXhvbnk7O0dlcm1hbnkNCmVtYWlsO2ludGVybmV0Omp1c3R1cy5zZWlm ZXJ0QGRlcmdsZWljaHJpY2h0ZXIuZGUNCnRlbDtjZWxsOis0OTE1NzMwNjQwNTA5DQp4LW1v emlsbGEtaHRtbDpGQUxTRQ0KdmVyc2lvbjoyLjENCmVuZDp2Y2FyZA0KDQo= --------------000109080709080302000708-- --lk4XmtVCdvckLhwdCcsdUVoOlJh0tOI6R Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJS2dBoAAoJELFJh75Z+IvIX4IP/3iPdgBgrb6w66yMG5imz2QE KbE8C44ADHLMxFwVEAdI8zlIxu1rErNSitCo1BNT15bTh/EQimz0fmfS7UcT2Pd5 Ab1oTUV0cZQlPmEB2tCskPG8hQshqcqTnIHtFeFhDkjC8hJ83zIreu8PwMPJgjwH 5Yjn5iiw49ScrmSZld1PWkncai50eOmC2wSuSvMpaCmqSe55mmMwW+dhlKKfb2wr 7DpqdNkZEbur1bNC/qOyLeSNwn2iEMaSX8Z+7/EevHaEpx/w3ZGlnHJs10n+nVup k8iGM7cHIg85IdmDKtwRiNywlFaUZAmmCRviXSXQPptOxh/cV73iFfwhn6Duf3lx 5H+DojVOBRhkZ3nGWjUFXV+LX5/sMhhLT+DWvaxB2jh01v6n91QVLn7WB1ulnQqA UNh7eiaNwM+vz1KGN6LFqjpNAod/EcjAcrxe8bB1LRGmxA0pxPrnxtSKn2RidZ8A 3MjWnfZwBO8QTeb+VqvDf0IWgvuxVvzhLcGP/sFqYvRjen4n+xs25xcE8c1Ao4PJ 1vYhXKs72PPeKO71ERnt21TmDA00wA+i12KeeR8cdT6hZZwHCX8f88MpOXjl6fQE d/I4wSQGGXJ9wkHyHh65QnjXOzMn7fHDPHb1iCRjm8OzTsxuDbuFXC5d48lgSc6r jERUHtD/WGBzHlT1dTck =4VOk -----END PGP SIGNATURE----- --lk4XmtVCdvckLhwdCcsdUVoOlJh0tOI6R--