From owner-freebsd-stable Wed Oct 18 17:35:26 2000 Delivered-To: freebsd-stable@freebsd.org Received: from mail2.uniserve.com (mail2.uniserve.com [204.244.156.10]) by hub.freebsd.org (Postfix) with ESMTP id E08DD37B4E5 for ; Wed, 18 Oct 2000 17:35:23 -0700 (PDT) Received: from shell.uniserve.ca ([204.244.186.218]) by mail2.uniserve.com with esmtp (Exim 3.13 #1) id 13m3fX-000AUD-00; Wed, 18 Oct 2000 17:34:51 -0700 Date: Wed, 18 Oct 2000 17:34:49 -0700 (PDT) From: Tom X-Sender: tom@shell.uniserve.ca To: Matt Dillon Cc: Mike Hoskins , Danny Braniss , Gerhard Sittig , freebsd-stable@FreeBSD.ORG Subject: Re: PERC2 RAID support in 4.1-STABLE In-Reply-To: <200010190023.e9J0N6e90640@earth.backplane.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Wed, 18 Oct 2000, Matt Dillon wrote: > :If memory serves, this is what I ordered on a couple of my new > :2450's... The 100MHz i960RX with 128MB cache. I'm planning to run some > :tests in RAID 1 and 10 modes. > : > :I'm not sure I fully understand why a lot of people are so caught up on > :RAID 5. RAID 1 seems fast and reliable given a decent controller with > :good recovery options, and RAID 10 sounds like a better solution with a > :larger quantity of drives. > > A mirrored setup (RAID-1) will be a whole lot faster then a parity > setup (RAID-5), since different read requests can be dispatched to > both sides of the mirror simultaniously and writing does not require > parity calculation. A RAID5 system can also send different read requests to different disks. Writing is another issue. Writing to a RAID5 volume can be costly. Writing is ususally one third the speed of reading, especially small random writes. Tom Uniserve To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message