From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Shubert Subject: Re: 3-drive RAID1 for my low use home server? Date: Wed, 24 Mar 2010 07:49:19 -0700 Message-ID: References: <5bdc1c8b1003231437q1cbeabex85833be0a59e3357@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5bdc1c8b1003231437q1cbeabex85833be0a59e3357@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Mark Knecht wrote: > Hi, > Just triple checking what I think I've learned here before I start > loading Gentoo. Parts are arriving and I'm staring to put them > together to build a combo low-use server (backups and MythTV) as well > as desktop for my wife. I can do anything up to 6 drives but want the > RAID to survive in the face of possibly two drive failure. This is all > low bandwidth stuff. > > I'm fairly focused at this point on doing RAID1 using 3 drives. > Unless I hear differently I believe a 3-drive RAID1 could survive 2 > drive failures, and as well any single drive could be taken to another > machine or even placed in an external USB/eSATA drive container in the > event of some major motherboard failure. Is any of that incorrect? All sounds right to me. Just be sure that the array is defined with 3 drives and no spares. > Also, along the way folks have mentioned hot spares but I'm not > seeing that a hot spare does much for RAID1. Am I incorrect about > that? Right. The only thing it would buy you is a little write performance, but you'd lose a little read performance, and take a performance hit if/when one drive goes off. > Granted, I guess the rebuild starts automatically and maybe > that's worth it, but I'm thinking that mdadm can probably let me know > fairly quickly that I need to do some work. I've purchased 6 drives so > I'll have 2 or 3 spares around and I can do a hot spare but I don't > see the value in spinning the drive for a year burning power and > wearing the drive out vs. just putting it on the shelf and keeping it > in reserve for a rainy day. Just one thought here. There is a certain "infant mortality syndrome" that drives experience (according to google study). I would rotate drives from the shelf into service after a year or so, while they're still under warranty (assuming 3yr warranty). If the warranty period is less than 2yr, rotate them sooner. NJoy! -- -Eric 'shubes'