From owner-freebsd-stable@FreeBSD.ORG Wed Jan 5 22:12:23 2011 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6D0291065674 for ; Wed, 5 Jan 2011 22:12:23 +0000 (UTC) (envelope-from artemb@gmail.com) Received: from mail-bw0-f54.google.com (mail-bw0-f54.google.com [209.85.214.54]) by mx1.freebsd.org (Postfix) with ESMTP id B17E58FC18 for ; Wed, 5 Jan 2011 22:12:22 +0000 (UTC) Received: by bwz12 with SMTP id 12so8619953bwz.13 for ; Wed, 05 Jan 2011 14:12:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:sender:received :in-reply-to:references:date:x-google-sender-auth:message-id:subject :from:to:cc:content-type; bh=s2NZrsv9h8LEzMlJsHK3RS/HRDs3+n4yFgGqGNf3yhE=; b=pbQQi5qljCaB+oxwtfuVXQOo8YT/uKpkNAFJPL9dMFMZYTATBB2exoxo7x9VEmwIrI REegdOCBi52B0b0Sw9J/eMjNIjnImZ34Xzd3wQ1DjFv28fA4ki4lsryQk+cxczETz2mN ssoThXHfRG9Ugoj4yIxGhyLKWpel4VBcEBxIs= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=hc0loAJZdZqZ9ssL0MffiW9yoF0fmS7d2xlKwJUFlCd0eJVqxCoyqvINbz5wqXGwt4 H5ByCMThSF5BQlGpV/gPvIpI4L6Che17dHBRaWGHcGbzeibjm3Mz9nCtpzfodGhYaLk7 pshVMUPTQt8bpTofUNbF54JdwhWnmLXKYARyE= MIME-Version: 1.0 Received: by 10.204.73.17 with SMTP id o17mr1551320bkj.26.1294265541749; Wed, 05 Jan 2011 14:12:21 -0800 (PST) Sender: artemb@gmail.com Received: by 10.204.22.18 with HTTP; Wed, 5 Jan 2011 14:12:21 -0800 (PST) In-Reply-To: <488AE93A-97B9-4F01-AD0A-0098E4B329C3@my.gd> References: <4D1C6F90.3080206@my.gd> <4D21E679.80002@my.gd> <84882169-0461-480F-8B4C-58E794BCC8E6@my.gd> <488AE93A-97B9-4F01-AD0A-0098E4B329C3@my.gd> Date: Wed, 5 Jan 2011 14:12:21 -0800 X-Google-Sender-Auth: Pjws985YJZLQewl9kI14N9v1Cyo Message-ID: From: Artem Belevich To: Damien Fleuriot Content-Type: text/plain; charset=ISO-8859-1 Cc: "freebsd-stable@freebsd.org" , Chris Forgeron Subject: Re: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Jan 2011 22:12:23 -0000 On Wed, Jan 5, 2011 at 1:55 PM, Damien Fleuriot wrote: > Well actually... > > raidz2: > - 7x 1.5 tb = 10.5tb > - 2 parity drives > > raidz1: > - 3x 1.5 tb = 4.5 tb > - 4x 1.5 tb = 6 tb , total 10.5tb > - 2 parity drives in split thus different raidz1 arrays > > So really, in both cases 2 different parity drives and same storage... In second case you get better performance, but lose some data protection. It's still raidz1 and you can't guarantee functionality in all cases of two drives failing. If two drives fail in the same vdev, your entire pool will be gone. Granted, it's better than single-vdev raidz1, but it's *not* as good as raidz2. --Artem