From owner-freebsd-questions@FreeBSD.ORG Thu Aug 28 14:28:08 2014 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 60871487 for ; Thu, 28 Aug 2014 14:28:08 +0000 (UTC) Received: from mail-qa0-f53.google.com (mail-qa0-f53.google.com [209.85.216.53]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 14E871CF3 for ; Thu, 28 Aug 2014 14:28:07 +0000 (UTC) Received: by mail-qa0-f53.google.com with SMTP id w8so771796qac.40 for ; Thu, 28 Aug 2014 07:28:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:mime-version:content-type:from :in-reply-to:date:cc:content-transfer-encoding:message-id:references :to; bh=ePL7M+GRHYZlBHB4o/FtaS8mZxHeoFTLvDp729yuk/0=; b=T4nhoehjizOM0ee+RYySlg4ZBW3Io7HQx292UiqSH9l8tHoRDohcOzS33bCSI2pDvT FmGRoafh6fwu/nTilxWj+fw1yYA7XSFdTY0cgpLQshwmcjFkp4+KvplhoKuEQae1FfwU 2tdYI1XzhnOMYLR7iWxgwhNyfGepTGusWuOkFWEOYcQhrrswfC2AaTYNZihNvbs+JyEo /2TWexTPuwLXZQru5ZJIASovlSJvEm88D0aBDynedLTEowTgOKabjBz2TWrxCDgNcFQD Gt/v7Yc5a30zUIe017mimsKrXbwPmt5uPFEH3sm2UGpe+Z+er86DBRlD75kGLDQhdrCU 7dFw== X-Gm-Message-State: ALoCoQmmvVRBoRSy4JJbrc4Vvf9RWzXA2ELPeUbjUt/eW/UqFybh6oPXhST4kS259OITXs9VGgNH X-Received: by 10.224.96.137 with SMTP id h9mr7160830qan.96.1409236081258; Thu, 28 Aug 2014 07:28:01 -0700 (PDT) Received: from [192.168.2.65] ([96.236.21.80]) by mx.google.com with ESMTPSA id a64sm5757512qge.22.2014.08.28.07.28.00 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 28 Aug 2014 07:28:00 -0700 (PDT) Subject: Re: gvinum raid5 vs. ZFS raidz Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Content-Type: text/plain; charset=us-ascii From: Paul Kraus In-Reply-To: <201408280636.s7S6a5OZ022667@sdf.org> Date: Thu, 28 Aug 2014 10:27:59 -0400 Content-Transfer-Encoding: quoted-printable Message-Id: <25B567A0-6639-41EE-AB3E-96AFBA3F11B7@kraus-haus.org> References: <201408020621.s726LsiA024208@sdf.org> <53DCDBE8.8060704@qeng-ho.org> <201408060556.s765uKJA026937@sdf.org> <53E1FF5F.1050500@qeng-ho.org> <201408070831.s778VhJc015365@sdf.org> <201408070936.s779akMv017524@sdf.org> <201408071106.s77B6JCI005742@sdf.org> <5B99AAB4-C8CB-45A9-A6F0-1F8B08221917@kraus-haus.org> <201408220940.s7M9e6pZ008296@sdf.org> <7971D6CA-AEE3-447D-8D09-8AC0B9CC6DBE@kraus-haus.org> <201408260641.s7Q6feBc004970@sdf.org> <9588077E-1198-45AF-8C4A-606C46C6E4F8@kraus-haus.org> <201408280636.s7S6a5OZ022667@sdf.org> To: Scott Bennett X-Mailer: Apple Mail (2.1878.6) Cc: freebsd-questions@freebsd.org, freebsd@qeng-ho.org, Trond.Endrestol@fagskolen.gjovik.no X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 28 Aug 2014 14:28:08 -0000 On Aug 28, 2014, at 2:36, Scott Bennett wrote: > Paul Kraus wrote: >> Wow. That implies you are hitting a drive with a very high = uncorrectable error rate since the drive did not report any errors and = the data is corrupt. I have yet to run into one of those. >=20 > How would an uncorrectable error be detected by the drive without = any > parity checking or hardware-implemented write-with-verify? I suppose my point was that an operation that is NOT flagged by the = drive as failing and DOES return faulty data is, by definition, an = uncorrectable error (as far as the drive is concerned). The point is = that an uncorrectable error (from the drive standpoint) is just that, an = error that the drive CANNOT detect. > Are you using any drives larger than 1 TB? I have been testing with a bunch of 2TB (3 HGST and 1 WD). I have been = using ZFS and it has not reported *any* checksum errors. I have put one of the 4 into production service (I needed a replacement = for a failed 1TB and did not have any more 1TB in stock). It has been = running for a couple weeks now with no checksum errors reported. My = zpool is 5 x 1TB RAIDz2 and it has about 2TB of data on it right now. > If so, try copying a 1.1 TB > file to one of them, and then trying comparing the copy against the = original. Hurmmm. I have not worked with individual files that large. What = filesystem are you using here?=20 > Out of the three drives I could test that way, I got that kind of = result on > two every time I tried it. One of the two was a new Samsung (i.e., a > Seagate), and the other was a refurbished Seagate supplied as a = replacement > under warranty. The third got a clean copy the first time and two = bytes with > single-bit errors on the second try. That one was also a refurbished = Seagate > provided under warranty. If you use ZFS on these drives and copy the same file do you get any = checksum errors? -- Paul Kraus paul@kraus-haus.org