From owner-freebsd-questions@FreeBSD.ORG Sun Feb 23 10:51:31 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 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id BBE92231 for ; Sun, 23 Feb 2014 10:51:31 +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)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 41A3410B9 for ; Sun, 23 Feb 2014 10:51:31 +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 (8.14.8/8.14.8) with ESMTP id s1NApQN5019980 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO) for ; Sun, 23 Feb 2014 10:51:26 GMT (envelope-from m.seaman@infracaninophile.co.uk) DKIM-Filter: OpenDKIM Filter v2.8.3 smtp.infracaninophile.co.uk s1NApQN5019980 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=infracaninophile.co.uk; s=201001-infracaninophile; t=1393152686; bh=PGsLMqOlRSysWmp+Pd5wj0+vFEOe9I5af9ChEGZxwvQ=; h=Date:From:To:Subject:References:In-Reply-To; z=Date:=20Sun,=2023=20Feb=202014=2010:51:25=20+0000|From:=20Matthew =20Seaman=20|To:=20freebsd-questi ons@freebsd.org|Subject:=20Re:=20ZFS=20on=20Hardware=20RAID=20cont roller|References:=20|In-Reply-To:=20; b=gqojKPxtgAtDzU/1SZ53qurnVCdB67mxiOgADMxwZ1nZxn2bVqD9h9DF1b/e9tuF8 bA61W0nrhlBFShyXv5ezyuHr9ZPUf/Wm6EcKZBzVv8pOXDtqBooWZ7M3oIAEuphxSS wXMKRHG5m4bMjP6St+uX5OkNiAZWgUTizZz0jOVQ= Message-ID: <5309D2AD.4060307@infracaninophile.co.uk> Date: Sun, 23 Feb 2014 10:51:25 +0000 From: Matthew Seaman User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: freebsd-questions@freebsd.org Subject: Re: ZFS on Hardware RAID controller References: In-Reply-To: X-Enigmail-Version: 1.6 OpenPGP: id=E7F39EBF Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="p2P12MfdVWmhXDwrST960CSeE2vfdbjT8" X-Virus-Scanned: clamav-milter 0.98.1 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 autolearn=ham version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on lucid-nonsense.infracaninophile.co.uk X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 23 Feb 2014 10:51:31 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --p2P12MfdVWmhXDwrST960CSeE2vfdbjT8 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 22/02/2014 20:22, freebsd@fongaboo.com wrote: > If I am planning to use ZFS on a machine where the drive controller > happens to be one that can be configured for some combination of > HARDWARE RAID... >=20 > I should configure it so that it does not concatenate/span/combine the > drives in any way at the hardware level. >=20 > I need to configure it as if it wasn't even a RAID controller, but > rather in a configuration where the motherboard/filesystem/OS will > initially see each physical drive as its own volume. The ideal is to get the RAID controller to pass-through all the actual disk devices as if it was a host-bus adapter. Then ZFS can interact directly with the drives, which generally gives the best results. Whether you can do this or not depends on what RAID controller hardware you are using. 3ware controllers used to be able to do this, but since they were borg'd by LSI a while back I don't know if that is still the case with their most recent models. Many LSI RAID controllers -- or controllers using LSI chipsets but rebadged by companies like Dell or HP -- can be reflashed as host bus adaptors. This is a widely recommended setup for building a ZFS box. Otherwise, if you can't get the drives passed-through, your next best bet is to create a bunch of single drive RAID-0 devices, and feed those to ZFS. mfiutil(8) has a command to do this: mfiutil -u0 create jbod 1,2,3,4 This prevents ZFS from having full control over the hardware -- instead, the RAID controller does various monitoring functions. ZFS shifts a lot of the functionality of a dedicated HW RAID card onto the main memory / CPU of a system, which should both save the cost of a specialised dedicated card and also allow more flexibility in throwing system resource at the disk IO subsystem as required by your workload. The term 'jbod' referred originally to a stand-alone disk array configured in this way as individual RAID-0 devices hence 'just a box of disks' but has since been retconned to mean 'just a bunch of disks': any set of hardrives attached to a machine and presented to the OS as individual drives or single disk RAID-0 devices, whether in the main chassis or otherwise. Cheers, Matthew --=20 Dr Matthew J Seaman MA, D.Phil. 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