From owner-freebsd-questions@FreeBSD.ORG Mon Nov 24 07:39:32 2014 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 111A69E1 for ; Mon, 24 Nov 2014 07:39:32 +0000 (UTC) Received: from smtp.infracaninophile.co.uk (smtp6.infracaninophile.co.uk [IPv6:2001:8b0:151:1:3cd3:cd67:fafa:3d78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "smtp.infracaninophile.co.uk", Issuer "ca.infracaninophile.co.uk" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 80E23959 for ; Mon, 24 Nov 2014 07:39:29 +0000 (UTC) Received: from seedling.black-earth.co.uk (seedling.black-earth.co.uk [81.2.117.99]) (authenticated bits=0) by smtp.infracaninophile.co.uk (8.14.9/8.14.9) with ESMTP id sAO7dDRi062504 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO) for ; Mon, 24 Nov 2014 07:39:13 GMT (envelope-from m.seaman@infracaninophile.co.uk) Authentication-Results: smtp.infracaninophile.co.uk; dmarc=none header.from=infracaninophile.co.uk DKIM-Filter: OpenDKIM Filter v2.9.2 smtp.infracaninophile.co.uk sAO7dDRi062504 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=infracaninophile.co.uk; s=201001-infracaninophile; t=1416814753; bh=HuDzjTK7zZokWCsso6qgvQwe/sGwh/+aR5WCcwLVVpI=; h=Date:From:To:Subject:References:In-Reply-To; z=Date:=20Mon,=2024=20Nov=202014=2007:39:13=20+0000|From:=20Matthew =20Seaman=20|To:=20freebsd-questi ons@freebsd.org|Subject:=20Re:=20How=20much=20space=20does=20raidz 2=20'eat'?|References:=20<20141123232623.39d46c80@falbala.rz1.conv enimus.net>=20<5472DB34.8080500@infracaninophile.co.uk>|In-Reply-T o:=20<5472DB34.8080500@infracaninophile.co.uk>; b=oNbUStFKtwYpMFVivkCFL1B9LbFkP+uzBatImK+7q+fQwzEnbg223NIuzVNn0FI42 H4nQ2olb3bCePX7amtHdYC/bHK78MEJbOPWZhikZuAZOgnBSqmSKjlN37OFEtTxqc6 jWEcsz5mktaIIv0Yiet9r5lneVi37PpHKC43se6Y= Message-ID: <5472E0A1.7050007@infracaninophile.co.uk> Date: Mon, 24 Nov 2014 07:39:13 +0000 From: Matthew Seaman User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: freebsd-questions@freebsd.org Subject: Re: How much space does raidz2 'eat'? References: <20141123232623.39d46c80@falbala.rz1.convenimus.net> <5472DB34.8080500@infracaninophile.co.uk> In-Reply-To: <5472DB34.8080500@infracaninophile.co.uk> OpenPGP: id=E1ECF9BB Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="5QBi5ddNhovnE28duRLT2qvotvQN9A8jI" X-Virus-Scanned: clamav-milter 0.98.4 at lucid-nonsense.infracaninophile.co.uk X-Virus-Status: Clean X-Spam-Status: No, score=-2.5 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lucid-nonsense.infracaninophile.co.uk 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: Mon, 24 Nov 2014 07:39:32 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --5QBi5ddNhovnE28duRLT2qvotvQN9A8jI Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 24/11/2014 07:16, Matthew Seaman wrote: > On 23/11/2014 22:26, Christian Baer wrote: >> After creating a raidz2 pool, I get this: >=20 >> Now I know that while WD works with kB, FreeBSD works with KiB (factor= >> 1024). However, if I break this drive down to that and multiply that b= y >> 5, I get 18.19TiB, while df gives me 16TiB. Sure, there is some >> overhead and all, but certainly (hopefully) not 2 whole TiB! That woul= d >> be more than 10%. >=20 > Use 'zpool list' to see the actual size and usage of your pool. >=20 > The amount you lose in overhead from partitioning and setting up geli > providers is pretty neglible; it's all down (oops. missed a bit) =2E.. in the noise with the TB scale drives you're using. > Yes, RAIDZ2 has around that level of overhead: think two parity blocks > for each three data blocks, so worst case is that about 40% of your raw= > space will disappear. The actual amount depends on exactly how many > drives you're using. >=20 >> Is this normal or am I missing something? >=20 > See: http://blog.delphix.com/matt/2014/06/06/zfs-stripe-width/ >=20 > Cheers, >=20 > Matthew >=20 --=20 Dr Matthew J Seaman MA, D.Phil. 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