From owner-freebsd-hackers@freebsd.org Tue Sep 15 23:01:51 2015 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 073999C2C90; Tue, 15 Sep 2015 23:01:51 +0000 (UTC) (envelope-from alex.burlyga.ietf@gmail.com) Received: from mail-vk0-x229.google.com (mail-vk0-x229.google.com [IPv6:2607:f8b0:400c:c05::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id B54D31170; Tue, 15 Sep 2015 23:01:50 +0000 (UTC) (envelope-from alex.burlyga.ietf@gmail.com) Received: by vkgd64 with SMTP id d64so90339911vkg.0; Tue, 15 Sep 2015 16:01:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; bh=q0yhzQavVtq1XHaKweWEIqwNGgW/5hbexLoMphim8pc=; b=DInN7ZnYWcdVC7UewLIicGBN5oj3ny8y/IeL0/9v5TGLTX9Ueoezayvbf6EcdjRRLj 5bXze5tMxwSXi3brEmnAygVSWbBNVja2Xpla3iNJHJmYjbtEfBurDBLjWu60CiVOZKFU LVz85jCfWG3lWJcbTQl8CeSzmaJus6x3eBFSJD8oRXIw0gzq1Kyy+xlQUHwMGfAdcT3k NN4fBb6Mw9z8/h3DQHioygvZr4oriPQU/I7dI+1IrjtpkQmLI6kxL62XqeGiO51HvX1R 20SKccZRTCkDsX6OajIDlnBH/lJnr6NN+TIiuPE3Q5oEa/1X/r3QqvZw7IhyhbnpchfF TR0g== MIME-Version: 1.0 X-Received: by 10.31.33.134 with SMTP id h128mr23799766vkh.138.1442358109882; Tue, 15 Sep 2015 16:01:49 -0700 (PDT) Received: by 10.103.81.193 with HTTP; Tue, 15 Sep 2015 16:01:49 -0700 (PDT) In-Reply-To: References: <41EFCF21-D3B0-4EC4-8EAB-417CA33821FC@netgate.com> <8435FBF3-2F8E-4A25-ABEA-B7038AFFE372@netgate.com> Date: Tue, 15 Sep 2015 16:01:49 -0700 Message-ID: Subject: Re: ECC support From: "alex.burlyga.ietf alex.burlyga.ietf" To: Igor Mozolevsky Cc: Jim Thompson , Hackers freeBSD , Dieter BSD , freebsd-hardware@freebsd.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Sep 2015 23:01:51 -0000 On Tue, Sep 15, 2015 at 3:52 PM, Igor Mozolevsky wr= ote: > On 15 September 2015 at 23:34, Jim Thompson wrote: > > > > >> I think you=E2=80=99ll find that the default for =E2=80=98scrub=E2=80=99= is off on most (perhaps >> all) boards. There are reasons, and these relate directly to >> =E2=80=9Csignificantly diminish system performance=E2=80=9D, (above), as= well as the >> greatly increased RAM sizes in use today. >> > > Perhaps I missed something- what point is it that you're trying to make? = I > was saying that scrubbing aims to remove errors at the source (cf. "on > demand") and prevent multi-bit errors that become detectable but > irrecoverable, or worse, undetectable. Get hit by a few of the latter two > at "interesting" points and you'd wish that scrubbing were on! > > And seriously, ECC scrubbing is slow but ZFS (or even hardware RAID) > scrubbing is lightning fast??! C'mon are we going for data integrity or > speed here?! If I remember correctly enabling Patrol Scrub guaranties that each address gets hit once per 24 hours. So on 128GB system you are generating maybe 1-2MiB/s of reads. I'd say it's a good trade-off if you bothered to put ECC memory in. > > =E2=80=99Scrub' was popular about a decade ago, when DDR2 RAM was around = $100/GB. >> DDR3-1600 is about $6/GB today. >> > > Yup- with a much higher density of smaller memory bits! ;-) > > -- > Igor M. > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org= "