From owner-freebsd-database Thu Apr 11 16: 9:28 2002 Delivered-To: freebsd-database@freebsd.org Received: from flake.decibel.org (flake.decibel.org [216.254.40.10]) by hub.freebsd.org (Postfix) with SMTP id 8EED437B405 for ; Thu, 11 Apr 2002 16:09:24 -0700 (PDT) Received: (qmail 8077 invoked by uid 1001); 11 Apr 2002 23:09:23 -0000 Date: Thu, 11 Apr 2002 18:09:23 -0500 From: "Jim C. Nasby" To: Francisco Reyes Cc: FreeBSD DB List Subject: Re: Raid configuration Message-ID: <20020411180923.O56810@flake.decibel.org> Reply-To: jim@nasby.net References: <20020329113017.L51218-100000@zoraida.natserv.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20020329113017.L51218-100000@zoraida.natserv.net>; from lists@natserv.com on Fri, Mar 29, 2002 at 11:33:16AM -0500 X-Operating-System: FreeBSD 4.5-STABLE i386 X-Distributed: Join the Effort! http://www.distributed.net Sender: owner-freebsd-database@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Fri, Mar 29, 2002 at 11:33:16AM -0500, Francisco Reyes wrote: > Anyone has any experience with FreeBSD + RAID + SQL database? > In particular I am using PostgreSQL > > I am leaning towards RAID 10 with 4 disks > Given that PostgreSQL doesn't support table-spaces yet I would have the > first two mirrored disk for the database and the other two for the logs. > FWIW, RAID10 is not two seperate mirrors, it's a single volume. It's either a mirror of two striped volumes (yuck), or a stripe of mirrored volumes. In either case, it's not two seperately addressable volumes as your database v. logs comment suggests. -- Jim C. Nasby (aka Decibel!) jim@nasby.net Member: Triangle Fraternity, Sports Car Club of America Give your computer some brain candy! www.distributed.net Team #1828 Windows: "Where do you want to go today?" Linux: "Where do you want to go tomorrow?" FreeBSD: "Are you guys coming, or what?" To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-database" in the body of the message From owner-freebsd-database Thu Apr 11 16:51: 8 2002 Delivered-To: freebsd-database@freebsd.org Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by hub.freebsd.org (Postfix) with ESMTP id EB59437B422 for ; Thu, 11 Apr 2002 16:50:22 -0700 (PDT) Received: by elvis.mu.org (Postfix, from userid 1061) id 7EB30AE165; Thu, 11 Apr 2002 16:50:22 -0700 (PDT) Date: Thu, 11 Apr 2002 16:50:22 -0700 From: David Drum To: FreeBSD DB List Subject: Re: Raid configuration Message-ID: <20020411235022.GA21045@elvis.mu.org> Mail-Followup-To: David Drum , FreeBSD DB List References: <20020329113017.L51218-100000@zoraida.natserv.net> <20020411180923.O56810@flake.decibel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20020411180923.O56810@flake.decibel.org> User-Agent: Mutt/1.3.27i Sender: owner-freebsd-database@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Quoth Jim C. Nasby: > FWIW, RAID10 is not two seperate mirrors, it's a single volume. It's > either a mirror of two striped volumes (yuck), or a stripe of mirrored > volumes. The first description you give is RAID 0+1, the second is RAID 1+0. There is a difference. If a disk goes bad in a RAID 0+1, you've lost an entire mirror, because the whole stripe is gone. If a disk goes bad in a RAID 1+0, you've only lost one mirrored drive, and not a whole stripe. mirror +-------------+ |strpA strpB | |+----+ +----+| || 1a | | 1b || RAID 0+1 (a mirror (RAID 0) of striped (RAID 1) drives) || | | || || 2a | | 2b || If one disk in the "a" stripe goes bad, the whole stripe || | | || is lost. So no matter how many disks are in the RAID, || 3a | | 3b || the loss of one results in a practical loss of 50%. |+----+ +----+| +-------------+ stripe +-------------+ | mirror1 | |+-----------+| || 1a 1b || RAID 0+1 (a mirror (RAID 0) of striped (RAID 1) drives) |+-----------+| | mirror2 | If any one disk in any of the three mirrors goes bad, |+-----------+| the stripe is still preserved. || 2a 2b || |+-----------+| | mirror3 | |+-----------+| || 3a 3b || |+-----------+| +-------------+ Regards, David Drum david@mu.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-database" in the body of the message From owner-freebsd-database Fri Apr 12 10:13:58 2002 Delivered-To: freebsd-database@freebsd.org Received: from mail.wolves.k12.mo.us (mail.wolves.k12.mo.us [207.160.214.1]) by hub.freebsd.org (Postfix) with ESMTP id F38A337B42A for ; Fri, 12 Apr 2002 10:13:50 -0700 (PDT) Received: from mail.wolves.k12.mo.us (cdillon@mail.wolves.k12.mo.us [207.160.214.1]) by mail.wolves.k12.mo.us (8.9.3/8.9.3) with ESMTP id MAA51374; Fri, 12 Apr 2002 12:13:27 -0500 (CDT) (envelope-from cdillon@wolves.k12.mo.us) Date: Fri, 12 Apr 2002 12:13:26 -0500 (CDT) From: Chris Dillon To: David Drum Cc: FreeBSD DB List Subject: Re: Raid configuration In-Reply-To: <20020411235022.GA21045@elvis.mu.org> Message-ID: <20020412120947.Q48494-100000@mail.wolves.k12.mo.us> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-database@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Thu, 11 Apr 2002, David Drum wrote: > Quoth Jim C. Nasby: > > > FWIW, RAID10 is not two seperate mirrors, it's a single volume. It's > > either a mirror of two striped volumes (yuck), or a stripe of mirrored > > volumes. > > The first description you give is RAID 0+1, the second is RAID 1+0. > There is a difference. If a disk goes bad in a RAID 0+1, you've lost an > entire mirror, because the whole stripe is gone. If a disk goes bad in > a RAID 1+0, you've only lost one mirrored drive, and not a whole stripe. And when you only have a four-drive configuration, it makes no difference which one you use since the chances of a total failure is exactly the same either way. Any more drives than that and you definately want RAID10. :-) -- Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net FreeBSD: The fastest and most stable server OS on the planet - Available for IA32 (Intel x86) and Alpha architectures - IA64, PowerPC, UltraSPARC, and ARM architectures under development - http://www.freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-database" in the body of the message