From owner-freebsd-questions@FreeBSD.ORG Tue Aug 26 13:50:41 2014 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 87D198B5 for ; Tue, 26 Aug 2014 13:50:41 +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 3D99538C9 for ; Tue, 26 Aug 2014 13:50:40 +0000 (UTC) Received: by mail-qa0-f53.google.com with SMTP id v10so13513184qac.40 for ; Tue, 26 Aug 2014 06:50:34 -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=ZTkGC/KUm/EFGA9bN19qaayTbn0pU6zgziPTnr5mtTc=; b=Z4hF6QQ3q9kya2JFmTpcaUKNnuJ2GDZ0g5lhnE3CdN4h45l466awzIbxNbXBKCbfdF N/jnxa+U3tfXe9SqsoDug3CAQa8E6UPU0nSYF0n8oqaD81ZS9TUTsxkxIRuCkmb+Xzkb rAeo6eKY2lDDOF908wsnDC+OrAakXE9ZqIMUaYs7GwjbkhSCekTns8eVlVgxQKqRGh/+ iXZY3Kt7k0WqOQxZEN03LAu+R9rEaZdVyEBi8mHnRfl4E2C5pMkgjjW8NdqF2YJ3o3Ki 5e7s2mM/saDI7kgKsN2ygRXwybL5Zusei9Yl5k3LZHxWreNgvqg+fR63zzCJOa5ckjBB fbLA== X-Gm-Message-State: ALoCoQk44Jm4kfOQbFbIGPxKhIUy4F5WpCKSmdpCBM3754LCWgxUGVG9r6QIPW0vmIiM/dSKJQJP X-Received: by 10.229.73.70 with SMTP id p6mr45370162qcj.13.1409060688015; Tue, 26 Aug 2014 06:44:48 -0700 (PDT) Received: from mbp-1.thecreativeadvantage.com (mail.thecreativeadvantage.com. [96.236.20.34]) by mx.google.com with ESMTPSA id e2sm9604449qas.38.2014.08.26.06.44.47 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 26 Aug 2014 06:44:47 -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: <201408260641.s7Q6feBc004970@sdf.org> Date: Tue, 26 Aug 2014 09:44:46 -0400 Content-Transfer-Encoding: quoted-printable Message-Id: <9588077E-1198-45AF-8C4A-606C46C6E4F8@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> 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: Tue, 26 Aug 2014 13:50:41 -0000 On Aug 26, 2014, at 2:41, Scott Bennett wrote: > Paul Kraus wrote: >> On Aug 22, 2014, at 5:40, Scott Bennett wrote: >>> What I'm seeing here is ~2 KB of errors out >>> of ~1.1TB, which is an error rate (in bytes, not bits) of ~1.82e+09, = and the >>> majority of the erroneous bytes I looked at had multibit errors. I = consider >>> that to be a huge change in the actual device error rates, specs be = damned. >>=20 >> That seems like a very high error rate. Is the drive reporting those = errors or are they getting past the drive?s error correction and showing = up as checksum errors in ZFS ? A drive that is throwing that many errors = is clearly defective or dying. >=20 > I'm not using ZFS yet. Once I get a couple more 2 TB drives, I'll = give > it a shot. > The numbers are from running direct comparisons between the source = file > and the copy of it using cmp(1). In one case, I ran the cmp twice and = got > identical results, which I interpret as an indication that the errors = are > occurring during the writes to the target disk during the copying. 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. -- Paul Kraus paul@kraus-haus.org