From owner-freebsd-stable@FreeBSD.ORG Sun Jan 9 10:50:11 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 5C489106564A for ; Sun, 9 Jan 2011 10:50:11 +0000 (UTC) (envelope-from m.seaman@infracaninophile.co.uk) Received: from smtp.infracaninophile.co.uk (smtp6.infracaninophile.co.uk [IPv6:2001:8b0:151:1:3fd3:cd67:fafa:3d78]) by mx1.freebsd.org (Postfix) with ESMTP id B2E148FC12 for ; Sun, 9 Jan 2011 10:50:10 +0000 (UTC) Received: from seedling.black-earth.co.uk (seedling.black-earth.co.uk [81.187.76.163]) (authenticated bits=0) by smtp.infracaninophile.co.uk (8.14.4/8.14.4) with ESMTP id p09Ao64M063668 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Sun, 9 Jan 2011 10:50:07 GMT (envelope-from m.seaman@infracaninophile.co.uk) X-DKIM: Sendmail DKIM Filter v2.8.3 smtp.infracaninophile.co.uk p09Ao64M063668 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=infracaninophile.co.uk; s=201001-infracaninophile; t=1294570207; bh=hk2qncK17lapUYR/03JgQtpYkeDg7tgwHQ/OylOCNBA=; h=Message-ID:Date:From:MIME-Version:To:CC:Subject:References: In-Reply-To:Content-Type:Cc:Content-Type:Date:From:In-Reply-To: Message-ID:Mime-Version:References:To; z=Message-ID:=20<4D2992D7.9090009@infracaninophile.co.uk>|Date:=20S un,=2009=20Jan=202011=2010:49:59=20+0000|From:=20Matthew=20Seaman= 20|User-Agent:=20Mozilla/5.0=20(M acintosh=3B=20U=3B=20Intel=20Mac=20OS=20X=2010.6=3B=20en-US=3B=20r v:1.9.2.13)=20Gecko/20101207=20Thunderbird/3.1.7|MIME-Version:=201 .0|To:=20Jean-Yves=20Avenard=20|CC:=20freebsd -stable@freebsd.org|Subject:=20Re:=20ZFS=20-=20moving=20from=20a=2 0zraid1=20to=20zraid2=20pool=20with=201.5tb=20disks|References:=20 <4D1C6F90.3080206@my.gd>=09=09<4D21E 679.80002@my.gd>=09<84882169-0461-480F-8B4C-58E794BCC8E6@my.gd>=09 =09< m262ty39th.wl%randy@psg.com>=09<4D297587.4030108@infracaninophile. co.uk>=09=09<4D2987E0.7060701@infracaninophile.co.uk>=20|In-Reply-To:=20 |X-E nigmail-Version:=201.1.1|OpenPGP:=20id=3D60AE908C|Content-Type:=20 multipart/signed=3B=20micalg=3Dpgp-sha1=3B=0D=0A=20protocol=3D"app lication/pgp-signature"=3B=0D=0A=20boundary=3D"------------enig378 6E061DB8ED58AB8E80202"; b=Ju+o/3Qm8lERI7yjEY4sxdMON2SrNCfZubzGEHFKJWVxCRXsOTpC/1WiVdjMVtcn9 Ms9O2FDzP3OXypeaZqiGqUmhHUm1haLIEmnr9ELLJQmDzSSXlz9tV/O7c1pd88O9nz O+/y48XsT9PEGl8wRXida6skoI04TgBAZAiJYAPE= Message-ID: <4D2992D7.9090009@infracaninophile.co.uk> Date: Sun, 09 Jan 2011 10:49:59 +0000 From: Matthew Seaman User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.13) Gecko/20101207 Thunderbird/3.1.7 MIME-Version: 1.0 To: Jean-Yves Avenard 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> In-Reply-To: X-Enigmail-Version: 1.1.1 OpenPGP: id=60AE908C Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig3786E061DB8ED58AB8E80202" X-Virus-Scanned: clamav-milter 0.96.5 at lucid-nonsense.infracaninophile.co.uk X-Virus-Status: Clean X-Spam-Status: No, score=0.7 required=5.0 tests=BAYES_50,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,SPF_FAIL autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on lucid-nonsense.infracaninophile.co.uk 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 10:50:11 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig3786E061DB8ED58AB8E80202 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 09/01/2011 10:24, Jean-Yves Avenard wrote: > On 9 January 2011 21:03, Matthew Seaman wrote: >=20 >> >> So you sacrifice performance 100% of the time based on the very unlike= ly >> possibility of drives 1+2 or 3+4 failing simultaneously, compared to t= he >> similarly unlikely possibility of drives 1+3 or 1+4 or 2+3 or 2+4 >=20 > But this is not what you first wrote What I said was: > >> Note: raidz2 on 4 disks doesn't really win you anything over 2 x mir= ror > >> pairs of disks, and the RAID10 mirror is going to be rather more performant. > You said the effect were identical. they are not. Which is certainly not saying the effects are identical. It's saying the difference is too small to worry about. > Plus, honestly, the difference in performance between raidz and raid10 > is also close to bein insignificant. That's not my experience. It depends on what sort of workload you have. If you're streaming very large files, I'd expect RAID10 and RAIDz to be about equal. If you're doing lots of randomly distributed small IOs, then RAID10 is going to win hands down. Cheers Matthew --=20 Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard Flat 3 PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate JID: matthew@infracaninophile.co.uk Kent, CT11 9PW --------------enig3786E061DB8ED58AB8E80202 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.16 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk0pkt4ACgkQ8Mjk52CukIyDZQCgjBDL3ih7jz1BaXw35vdNBsrM wbcAn3u2gPHMH2bnHp+0JBod02aTKrq2 =+29H -----END PGP SIGNATURE----- --------------enig3786E061DB8ED58AB8E80202--