From owner-freebsd-stable@FreeBSD.ORG Sun Jan 9 10:24:37 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 0B9FC106566B for ; Sun, 9 Jan 2011 10:24:37 +0000 (UTC) (envelope-from jyavenard@gmail.com) Received: from mail-iy0-f182.google.com (mail-iy0-f182.google.com [209.85.210.182]) by mx1.freebsd.org (Postfix) with ESMTP id C23488FC16 for ; Sun, 9 Jan 2011 10:24:36 +0000 (UTC) Received: by iyb26 with SMTP id 26so17712330iyb.13 for ; Sun, 09 Jan 2011 02:24:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=3Co05Z50R707wHH0cyy8E+Gs0HyITBFX2E0wrF/b3tg=; b=LQWs5lENcyqWRJwrCxkg9TePKU6EFG8CkwXr0q7Pzpmfz0+dkt4CFE5Epr+MN4yRLl BiAb4mj3z75nBKH0WX7b2ZpZv30jkET5hRHRra71Gv6wJ9sRCmolnfKOE9s+NjqsaZX8 5NyR+v0NwGTG2zLd9j4Nfmmlf6qiErE9x+U7g= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=Xa4F6zvfo4mljlVSt9sjTGnQuUTWfa0W6Gx5hf5pg5vQVaa2xqD4glqjYOgFmT8H3B 6lcVN0hYwsAyRUtwrTEJlrB3G1qXgZUe9TyIuM712TOqSwcFDA4VqfYYuRt2TcIqLQ+K X6Cbv3ZvOzxwq16GtR7KYh7yUGomPNSpqI4vg= MIME-Version: 1.0 Received: by 10.42.177.196 with SMTP id bj4mr2943254icb.129.1294568676107; Sun, 09 Jan 2011 02:24:36 -0800 (PST) Received: by 10.42.172.69 with HTTP; Sun, 9 Jan 2011 02:24:36 -0800 (PST) In-Reply-To: <4D2987E0.7060701@infracaninophile.co.uk> References: <4D1C6F90.3080206@my.gd> <4D21E679.80002@my.gd> <84882169-0461-480F-8B4C-58E794BCC8E6@my.gd> <4D297587.4030108@infracaninophile.co.uk> <4D2987E0.7060701@infracaninophile.co.uk> Date: Sun, 9 Jan 2011 21:24:36 +1100 Message-ID: From: Jean-Yves Avenard To: Matthew Seaman Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: freebsd-stable@freebsd.org 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: Sun, 09 Jan 2011 10:24:37 -0000 On 9 January 2011 21:03, Matthew Seaman w= rote: > > So you sacrifice performance 100% of the time based on the very unlikely > possibility of drives 1+2 or 3+4 failing simultaneously, compared to the > similarly unlikely possibility of drives 1+3 or 1+4 or 2+3 or 2+4 But this is not what you first wrote You said the effect were identical. they are not. Now if you want to favour performance over redundancy that's ultimately up to the user... Plus, honestly, the difference in performance between raidz and raid10 is also close to bein insignificant. > failing simultaneously?[*] =A0That's not a trade-off worth making IMHO. > If the data is that valuable, you should be making copies of it to some > independent machine all the time and backing up at frequent intervals, > which backups you keep off-site in disaster-proof storage.