From owner-freebsd-questions@FreeBSD.ORG Sat Jun 28 07:57:08 2008 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 1C62A106568B for ; Sat, 28 Jun 2008 07:57:08 +0000 (UTC) (envelope-from prad@towardsfreedom.com) Received: from pd3mo1so.prod.shaw.ca (idcmail-mo1so.shaw.ca [24.71.223.10]) by mx1.freebsd.org (Postfix) with ESMTP id EACB58FC0C for ; Sat, 28 Jun 2008 07:57:07 +0000 (UTC) (envelope-from prad@towardsfreedom.com) Received: from pd2mr4so.prod.shaw.ca (pd2mr4so-qfe3.prod.shaw.ca [10.0.141.107]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0K3500CK4Y37BB40@l-daemon> for freebsd-questions@freebsd.org; Sat, 28 Jun 2008 01:57:07 -0600 (MDT) Received: from pn2ml9so.prod.shaw.ca ([10.0.121.7]) by pd2mr4so.prod.shaw.ca (Sun Java System Messaging Server 6.2-7.05 (built Sep 5 2006)) with ESMTP id <0K35005F0Y37MN10@pd2mr4so.prod.shaw.ca> for freebsd-questions@freebsd.org; Sat, 28 Jun 2008 01:57:08 -0600 (MDT) Received: from gom.home ([70.67.160.176]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0K3500E04Y36JN30@l-daemon> for freebsd-questions@freebsd.org; Sat, 28 Jun 2008 01:57:06 -0600 (MDT) Received: from gom.home (localhost [127.0.0.1]) by gom.home (Postfix) with ESMTP id 4BCC0B842 for ; Sat, 28 Jun 2008 00:57:02 -0700 (PDT) Date: Sat, 28 Jun 2008 00:57:02 -0700 From: prad To: freebsd-questions@freebsd.org Message-id: <20080628005702.2137bb8c@gom.home> MIME-version: 1.0 X-Mailer: Claws Mail 3.3.1 (GTK+ 2.12.1; i386-portbld-freebsd7.0) Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7bit Subject: first pre-emptive raid 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, 28 Jun 2008 07:57:08 -0000 our dual pentium3 1GHz with 2G ram and 8 18G scsi drives (server holds 4) should be arriving in about 1 week. my son and i want to this up as proper server rather than as a desktopish installation being used as a server. it will serve primarily websites (static html) and email for virtual domains as well as implement dns. from the handbook, we are learning 1. how to installing scsi drives (we have some old 2G) from #18.3 2. about software raid #18.4.1 (because we don't have a hardware solution and i guess you really don't have anything to figure out with one) 3. about geom #19 and vinum #20 4. about raid principles in general from wikipedia after a first reading, some initial questions about items: 3. it seems that geom just does striping and mirroring, but vinum offers more configurability and is really the preferred choice? 4.1 with 4 18G drives one thought is to do a raid1, but we really don't want 3 identical copies. is the only way to have 2 36G mirrors, by using raid0+1 or raid1+0? 4.2 another possibility is to do raid0, but is that ever wise unless you desperately need the space since in our situation you run a 1/4 chance of going down completely? 4.3 is striping or mirroring faster as far as i/o goes (or does the difference really matter)? i would have thought the former, but the handbook says "Striping requires somewhat more effort to locate the data, and it can cause additional I/O load where a transfer is spread over multiple disks" #20.3 4.4 vinum introduces raid5 with striping and data integrity, but exactly what are the parity blocks? furthermore, since the data is striped, how can the parity blocks rebuild anything from a hard drive that has crashed? surely, the data from each drive can't be duplicated somehow over all the drives though #20.5.2 Redundant Data Storage has me scratching my head! if there is complete mirroring, wouldn't the disk space be cut in half as with raid1? this is all very interesting and very new to us. -- In friendship, prad ... with you on your journey Towards Freedom http://www.towardsfreedom.com (website) Information, Inspiration, Imagination - truly a site for soaring I's