From owner-freebsd-questions@FreeBSD.ORG Wed Feb 9 17:14:48 2011 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 5235E106564A for ; Wed, 9 Feb 2011 17:14:48 +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 A800E8FC1B for ; Wed, 9 Feb 2011 17:14:47 +0000 (UTC) Received: from russet.local (reflex.squiz.co.uk [83.217.109.164]) (authenticated bits=0) by smtp.infracaninophile.co.uk (8.14.4/8.14.4) with ESMTP id p19HEbkY046018 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Wed, 9 Feb 2011 17:14:43 GMT (envelope-from m.seaman@infracaninophile.co.uk) X-DKIM: Sendmail DKIM Filter v2.8.3 smtp.infracaninophile.co.uk p19HEbkY046018 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=infracaninophile.co.uk; s=201001-infracaninophile; t=1297271684; bh=+1pLKSggsl2SlmgwMjNcCNbquPw/7oanWynHIX0RxwU=; 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<4D52CB7C.3040004@infracaninophile.co.uk>|Date:=20W ed,=2009=20Feb=202011=2017:14:36=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:=20"$witch"=20|CC:=20freebsd-questio ns@freebsd.org|Subject:=20Re:=20ZFS=20over=20RAID6|References:=20< 4D52B0F6.9000006@rfc1925.net>|In-Reply-To:=20<4D52B0F6.9000006@rfc 1925.net>|X-Enigmail-Version:=201.1.1|Content-Type:=20multipart/si gned=3B=20micalg=3Dpgp-sha1=3B=0D=0A=20protocol=3D"application/pgp -signature"=3B=0D=0A=20boundary=3D"------------enig33696F060C05D08 667A1D00F"; b=YIgBxbZ05I4BWztuHS9LINlctMR+SGtNZUw6M2ejzj3FDYxU1fqlNAmOKh8upOeEE dBcH3l4KqToPTZTR7vmJLBwitQov4PYVTMKGFm6woaV5D3nzWIj/lfeO+QpOD8AO3d LmDc2oOPYk2zZj7D1hD7F4xOXGT0p/luY0lJ7ohU= X-Authentication-Warning: lucid-nonsense.infracaninophile.co.uk: Host reflex.squiz.co.uk [83.217.109.164] claimed to be russet.local Message-ID: <4D52CB7C.3040004@infracaninophile.co.uk> Date: Wed, 09 Feb 2011 17:14:36 +0000 From: Matthew Seaman User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.13) Gecko/20101207 Thunderbird/3.1.7 MIME-Version: 1.0 To: "$witch" References: <4D52B0F6.9000006@rfc1925.net> In-Reply-To: <4D52B0F6.9000006@rfc1925.net> X-Enigmail-Version: 1.1.1 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig33696F060C05D08667A1D00F" X-Virus-Scanned: clamav-milter 0.96.5 at lucid-nonsense.infracaninophile.co.uk X-Virus-Status: Clean X-Spam-Status: No, score=-0.1 required=5.0 tests=BAYES_40,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-questions@freebsd.org Subject: Re: ZFS over RAID6 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: Wed, 09 Feb 2011 17:14:48 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig33696F060C05D08667A1D00F Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 09/02/2011 15:21, $witch wrote: > considerations : >=20 > at lower level feel RAID6 meet my requirements (i love something that > can face a double hw fault) With ZFS that's called RAIDZ2 -- it's similar to RAID6 and it has the same two-failure resilience characteristic. > while at upper level ZFS looks very nice so am looking for such a > combination. >=20 >=20 > status : >=20 > as now had found some ADPTEC, ARECA and 3WARE adapters that look > reasonable but controller is not all; > i need also 8 (+ 2 spare) HDs and a case where to keep them. >=20 > so had extended research to 8HD cases with RAID6 capabilities. Mixing ZFS and standard H/W Raid is not a good idea -- ZFS expects to run on a collection of hard drives, not a composite disk array. Instead of paying for a RAID controller, put the money towards extra RAM and/or SSD cards to use for the ARC and the ZIL used by ZFS. If you want ZFS but you're stuck with built-in RAID, then it's best to configure the RAID as a JBOD and use ZFS over that. Hot spares and ZFS is a current development topic on FreeBSD: automatic replacement of a failed drive doesn't work properly. However, it should be relatively easy for an admin to type commands to achieve the same effe= ct. 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 --------------enig33696F060C05D08667A1D00F 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 v2.0.14 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk1Sy3wACgkQ8Mjk52CukIzfxgCdFo3UmWMOgbcHuHuE57ose0G8 CDoAnR1o6foflarY9Qz7au/Z7/dHos1E =xuai -----END PGP SIGNATURE----- --------------enig33696F060C05D08667A1D00F--