From owner-freebsd-questions@FreeBSD.ORG Sun Aug 9 09:01:43 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B116D106564A for ; Sun, 9 Aug 2009 09:01:43 +0000 (UTC) (envelope-from comp.john@googlemail.com) Received: from mail-bw0-f206.google.com (mail-bw0-f206.google.com [209.85.218.206]) by mx1.freebsd.org (Postfix) with ESMTP id 3AB1D8FC20 for ; Sun, 9 Aug 2009 09:01:42 +0000 (UTC) Received: by bwz2 with SMTP id 2so1533669bwz.43 for ; Sun, 09 Aug 2009 02:01:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=73c5kd0nJzQb5gTvvh/yEl2qwOfgk4lPFh4T8q/0o7w=; b=MkVs5zXgdH7TpeqchyOEt5/KH3FchZbO6uiQzx2mTf07p68Gr1AMo/X9Mpc1l0Vq3N E5jN7hqaTOqMyGYziPHUUgfAcy6L/8K34OHIB6AKwJL9/0AQ117WgfkmcUdOBlz9F7o/ l6W/V3FIwVYtVc24t8/Q9ofzs+QKNmFW2RFDw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=b0S/kX1zhdpfqaujapE2vy9C395fcu89msdd282R3IZjbRoQNKCBF/QC3SDlMaSO4r DkkGcuqJTxR0ucA6QOcWrbsn6Mv4by+jf7UXlWSaxcWUCJvLcBRPfTDbFshJaukz5z1e l9Osis9KMlndH90KIOV9kALH5DSpMpOozDT/Q= MIME-Version: 1.0 Received: by 10.223.108.210 with SMTP id g18mr712687fap.6.1249808501866; Sun, 09 Aug 2009 02:01:41 -0700 (PDT) In-Reply-To: References: Date: Sun, 9 Aug 2009 10:01:41 +0100 Message-ID: From: "John ." To: freebsd-questions@freebsd.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: Re: a (hopefully) simple newbie zfs query regarding available space X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Aug 2009 09:01:43 -0000 2009/8/9 chris scott : > > not a zfs thing is happens with all os and file systems. Basically HD > manufacturers quote their capacities in base 10 ie 1 TB =3D 1000000000 by= tes. > File systems are calculated in binary therefore the calculation they use = is > 1024 x 1024 x 1024 =3D 1099511627776. Slightly more as you can see. > > Therefore 1 GB is os terms is 1073741824 > > therefore hd capacity in GB is > > 1000000000000/1073741824 =3D 931.322575 > > The extra you see is it due to HD manufactures slightly over capacity the > drives > Hi, What I meant was, I was seeing 931MB instead of 1.6TB (2x1TB disks) but this was because I didn't read about zfs properly (they recommend 3 or more disks. In the man page for zpool it says: "A =A0raidz group with N disks of size X with P parity disks can hold approximately (N-P)*X bytes [...] The recommended number is between 3 and 9" so, I'll wait till I get an array before implementing zfs. In the meantime, I'm using gconcat. Sorry for the noise. --=20 John