From owner-freebsd-performance@FreeBSD.ORG Wed Sep 3 12:47:40 2003 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id F167D16A4BF for ; Wed, 3 Sep 2003 12:47:40 -0700 (PDT) Received: from odin.ac.hmc.edu (Odin.AC.HMC.Edu [134.173.32.75]) by mx1.FreeBSD.org (Postfix) with ESMTP id 29AFE43FDF for ; Wed, 3 Sep 2003 12:47:40 -0700 (PDT) (envelope-from brdavis@odin.ac.hmc.edu) Received: from odin.ac.hmc.edu (IDENT:brdavis@localhost.localdomain [127.0.0.1]) by odin.ac.hmc.edu (8.12.9/8.12.3) with ESMTP id h83JlY7c018563; Wed, 3 Sep 2003 12:47:34 -0700 Received: (from brdavis@localhost) by odin.ac.hmc.edu (8.12.9/8.12.3/Submit) id h83JlYp6018562; Wed, 3 Sep 2003 12:47:34 -0700 Date: Wed, 3 Sep 2003 12:47:34 -0700 From: Brooks Davis To: Chuck Swiger Message-ID: <20030903194734.GA7936@Odin.AC.HMC.Edu> References: <3F5634FE.9080303@mac.com> <20030903184506.GC14797@sgh.waw.pl> <3F5642FF.6060702@mac.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="XsQoSWH+UP9D9v3l" Content-Disposition: inline In-Reply-To: <3F5642FF.6060702@mac.com> User-Agent: Mutt/1.5.4i X-Virus-Scanned: by amavisd-milter (http://amavis.org/) on odin.ac.hmc.edu cc: freebsd-performance@freebsd.org Subject: Re: 20TB Storage System (fsck????) X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Sep 2003 19:47:41 -0000 --XsQoSWH+UP9D9v3l Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Sep 03, 2003 at 03:37:35PM -0400, Chuck Swiger wrote: > Piotr KUCHARSKI wrote: > >On Wed, Sep 03, 2003 at 02:37:50PM -0400, Chuck Swiger wrote: > >>I'm wary of the write-performance hit from putting too many drives wide= =20 > >>in a RAID-5 (or -5,0) configuration.=20 > > > >How many is "too many"? >=20 > At one point, the advice used to be to use between four and seven disks f= or=20 > a RAID-5 volume. For example, the Apple XServe RAID box has 14 bays, but= =20 > Apple seems to recommend configuring it as two 7-drive RAID-5 volumes,=20 > rather than a single 14-drive-wide RAID-5 volume. As far as I can tell from taking one of ours apart, that's not recommendation, that's a hard limit due to the system design. The XServe RAID is two 100% independent 7-disk RAID systems. If you look at the controller boards, each one has four High-Point ATA controllers which means it can only access 8 disks with reasonable performance. There appears to be no communication between the halves of the systems. -- Brooks --=20 Any statement of the form "X is the one, true Y" is FALSE. PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4 --XsQoSWH+UP9D9v3l Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) iD8DBQE/VkVVXY6L6fI4GtQRAjH7AJ0Wy7SliPnuHDctJtcZ4o2XA7B9JACgtVwq rl01HZTF3w6O3FU1qMi2BTY= =K9k3 -----END PGP SIGNATURE----- --XsQoSWH+UP9D9v3l--