From owner-freebsd-questions@FreeBSD.ORG Sun Jun 15 21:04:15 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 500E11065677 for ; Sun, 15 Jun 2008 21:04:15 +0000 (UTC) (envelope-from SRS0=B0FCMv=W5=shell.siscom.net=vogelke@siscom.net) Received: from lamorack.siscom.net (lamorack.siscom.net [209.251.2.116]) by mx1.freebsd.org (Postfix) with ESMTP id 260E28FC12 for ; Sun, 15 Jun 2008 21:04:15 +0000 (UTC) (envelope-from SRS0=B0FCMv=W5=shell.siscom.net=vogelke@siscom.net) Received: from shell.siscom.net ([209.251.2.80]) by lamorack.siscom.net with esmtp (Exim 4.62) (envelope-from ) id 1K7z80-0001GA-Ry for freebsd-questions@freebsd.org; Sun, 15 Jun 2008 16:47:08 -0400 Received: by shell.siscom.net (Postfix, from userid 2198) id B443A115529; Sun, 15 Jun 2008 16:47:08 -0400 (EDT) Received: by kev.msw.wpafb.af.mil (Postfix, from userid 32768) id C991BB7BA; Sun, 15 Jun 2008 16:46:37 -0400 (EDT) To: freebsd-questions@freebsd.org In-reply-to: <20080609232736.X39884@wojtek.tensor.gdynia.pl> (message from Wojciech Puchar on Mon, 9 Jun 2008 23:31:35 +0200 (CEST)) Organization: Oasis Systems Inc. X-Disclaimer: I don't speak for the USAF or Oasis. X-GPG-ID: 1024D/711752A0 2006-06-27 Karl Vogel X-GPG-Fingerprint: 56EB 6DBF 4224 C953 F417 CC99 4C7C 7D46 7117 52A0 Message-Id: <20080615204637.C991BB7BA@kev.msw.wpafb.af.mil> Date: Sun, 15 Jun 2008 16:46:37 -0400 (EDT) From: vogelke+software@pobox.com (Karl Vogel) Subject: Re: FreeBSD + ZFS on a production server? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: vogelke+software@pobox.com List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 15 Jun 2008 21:04:15 -0000 >> On Mon, 9 Jun 2008 23:31:35 +0200 (CEST), >> Wojciech Puchar said: W> but why you need [a filesystem for linux that do checksum on the fly]?! all W> PATA/SATA drives do checksumming on every read. in hardware, no CPU load. These days, hardware isn't just hardware. A disk drive can have around 300,000 lines of low-level firmware, and who wants to bet that it's completely bug-free? Silent-write errors are actually a big problem: http://www.usenix.org/publications/login/2008-06/openpdfs/bairavasundaram.pdf An Analysis of Data Corruption in the Storage Stack "In this paper, we present the first large-scale study of data corruption. We analyze corruption instances recorded in production storage systems containing a total of 1.53 million disk drives, over a period of 41 months. We study three classes of corruption: checksum mismatches, identity discrepancies, and parity inconsistencies. We focus on checksum mismatches since they occur the most; more than 400,000 instances of checksum mismatches over the 41-month period." -- Karl Vogel I don't speak for the USAF or my company Mangled song lyric: Looks like tomatoes Actual lyric: Looks like we made it. (Barry Mannilow)