From owner-freebsd-questions@FreeBSD.ORG Sat Jul 16 15:15:43 2005 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D747216A41C for ; Sat, 16 Jul 2005 15:15:43 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7AF2C43D49 for ; Sat, 16 Jul 2005 15:15:43 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from localhost (localhost [127.0.0.1]) by pi.codefab.com (Postfix) with ESMTP id CEA3C5E33; Sat, 16 Jul 2005 11:15:42 -0400 (EDT) Received: from pi.codefab.com ([127.0.0.1]) by localhost (pi.codefab.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 46182-05; Sat, 16 Jul 2005 11:15:33 -0400 (EDT) Received: from [192.168.1.3] (pool-68-161-54-113.ny325.east.verizon.net [68.161.54.113]) by pi.codefab.com (Postfix) with ESMTP id 199F95C99; Sat, 16 Jul 2005 11:15:33 -0400 (EDT) Message-ID: <42D9249A.2050007@mac.com> Date: Sat, 16 Jul 2005 11:15:38 -0400 From: Chuck Swiger Organization: The Courts of Chaos User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Nikolas Britton References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: amavisd-new at codefab.com Cc: FreeBSD - Questions Subject: Re: RAID Level 55 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: Sat, 16 Jul 2005 15:15:44 -0000 Nikolas Britton wrote: > I was reading on wikipedia about RAIDs trying to pass the time and I > was thinking why not have RAID 5+5 or 5+5+5 levels, sure you waste > 2/3th's of your space but wouldn't this be a killer setup for a > directory server where fast reads are of the utmost importance? Actually, no. RAID-5 prioritizes cost and reliability at the expense of performance. RAID-5 does adequate for read-mostly volumes with big files, and does worst with lots of writes to small files. RAID-5,0 or -1,0 would be a much better choice. > Would you add up the transfer rates for each drive to get the total > transfer rate of the array?, if true you could easily saturate a 10 > gigabit ethernet connection with a 555 array of IDE or SATA drives. Nope. Most machines are limited by their PCI bus and chipset to less than 1Gb/s of backplace bandwidth, although the higher-end boxes with multiple PCI busses or PCIe will do better. -- -Chuck