From owner-freebsd-questions@FreeBSD.ORG Thu May 23 09:00:24 2013 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 4000287D for ; Thu, 23 May 2013 09:00:24 +0000 (UTC) (envelope-from Albert.Shih@obspm.fr) Received: from smtp-int-m.obspm.fr (smtp-int-m.obspm.fr [145.238.187.15]) by mx1.freebsd.org (Postfix) with ESMTP id B305DE52 for ; Thu, 23 May 2013 09:00:23 +0000 (UTC) Received: from pcjas.obspm.fr (pcjas.obspm.fr [145.238.184.233]) by smtp-int-m.obspm.fr (8.14.3/8.14.3/SIO Observatoire de Paris - 07/2009) with ESMTP id r4N90LfO029449 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Thu, 23 May 2013 11:00:22 +0200 Date: Thu, 23 May 2013 11:00:21 +0200 From: Albert Shih To: Paul Kraus Subject: Re: ZFS install on a partition Message-ID: <20130523090021.GD1426@pcjas.obspm.fr> References: <372082cab2064846809615a8073e022c@DB3PR07MB059.eurprd07.prod.outlook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Miltered: at smtp-int-m.obspm.fr with ID 519DDAA5.000 by Joe's j-chkmail (http : // j-chkmail dot ensmp dot fr)! X-j-chkmail-Enveloppe: 519DDAA5.000/145.238.184.233/pcjas.obspm.fr/pcjas.obspm.fr/ Cc: Ivailo Tanusheff , Liste FreeBSD X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 May 2013 09:00:24 -0000 Le 18/05/2013 ? 09:02:15-0400, Paul Kraus a écrit > On May 18, 2013, at 3:21 AM, Ivailo Tanusheff > wrote: > > > If you use HBA/JBOD then you will rely on the software RAID of the > > ZFS system. Yes, this RAID is good, but unless you use SSD disks to > > boost performance and a lot of RAM the hardware raid should be more > > reliable and mush faster. > > Why will the hardware raid be more reliable ? While hardware raid is > susceptible to uncorrectable errors from the physical drives > (hardware raid controllers rely on the drives to report bad reads and > writes), and the uncorrectable error rate for modern drives is such > that with high capacity drives (1TB and over) you are almost certain > to run into a couple over the operational life of the drive. 10^-14 > for cheap drives and 10^-15 for better drives, very occasionally I > see a drive rated for 10^-16. Run the math and see how many TB worth > of data you have to write and read (remember these failures are > generally read failures with NO indication that a failure occurred, > bad data is just returned to the system). > > In terms of performance HW raid is faster, generally due to the cache > RAM built into the HW raid controller. ZFS makes good use of system, Before I'm installing my server under 9.0 + ZFS I do some benchmarks with ionice to compare FreeBSD 9.0+ ZFS + 12 disk SATA 7200 rpm vs CentOS + H700 + 12 disk SAS 15krpm (Both are same Dell poweredge). And the ZFS+12 disk sata goes much faster than CentOS+H700+ext4 almost everywhere. Only for small file AND small record size the ZFS is slower than CentOS. The server don't have SSD. He got 48Go of ram. Regards. JAS -- Albert SHIH DIO bâtiment 15 Observatoire de Paris 5 Place Jules Janssen 92195 Meudon Cedex France Téléphone : +33 1 45 07 76 26/+33 6 86 69 95 71 xmpp: jas@obspm.fr Heure local/Local time: jeu 23 mai 2013 10:53:50 CEST