From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1Q8uxG-0001bY-4i for garchives@archives.gentoo.org; Sun, 10 Apr 2011 13:45:30 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 6FEB91C025; Sun, 10 Apr 2011 13:43:21 +0000 (UTC) Received: from mail.ukfsn.org (mail.ukfsn.org [77.75.108.10]) by pigeon.gentoo.org (Postfix) with ESMTP id 2037A1C025 for ; Sun, 10 Apr 2011 13:43:20 +0000 (UTC) Received: from localhost (smtp-filter.ukfsn.org [192.168.54.205]) by mail.ukfsn.org (Postfix) with ESMTP id 3547EDEC25 for ; Sun, 10 Apr 2011 14:43:20 +0100 (BST) Received: from mail.ukfsn.org ([192.168.54.25]) by localhost (smtp-filter.ukfsn.org [192.168.54.205]) (amavisd-new, port 10024) with ESMTP id Sd0-8f4pKQiW for ; Sun, 10 Apr 2011 14:43:20 +0100 (BST) Received: from wstn.localnet (unknown [78.32.181.186]) by mail.ukfsn.org (Postfix) with ESMTP id E8220DEC22 for ; Sun, 10 Apr 2011 14:43:19 +0100 (BST) From: Peter Humphrey Organization: at home To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] [OT] Disk recommendations? Date: Sun, 10 Apr 2011 14:43:18 +0100 User-Agent: KMail/1.13.5 (Linux/2.6.36-gentoo-r8; KDE/4.4.5; x86_64; ; ) References: <201104092100.19783.peter@humphrey.ukfsn.org> <201104100850.41768.peter@humphrey.ukfsn.org> <1DE2A557-8514-43FD-8EF5-ECA09B9854EB@stellar.eclipse.co.uk> In-Reply-To: <1DE2A557-8514-43FD-8EF5-ECA09B9854EB@stellar.eclipse.co.uk> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201104101443.18963.peter@humphrey.ukfsn.org> X-Archives-Salt: X-Archives-Hash: 35239fe316935a6e7b95b8817bfe3f3d On Sunday 10 April 2011 12:53:39 Stroller wrote: > On 10/4/2011, at 8:50am, Peter Humphrey wrote: > > ... > > I'm just speculating at the moment, from a dabbler's point of view; what > > benefits would accrue from switching from RAID-1 to RAID-5 or above? > > And, in particular, what are the comparative virtues of the Samsung > > disks? > > In your previous message you mention "adding robustness", I don't think > you'd change from RAID1 in that case. > > RAID5 is less redundant than RAID1, but offers more space per drive. > > Either will continue to run if one drive fails, but RAID5 consists of more > drives (each of which has the potential for failure). > > RAID1 has 2 disks and offers up to 1/2 redundancy. 1/2 your disks can fail > without loss of data. > > RAID5 has X disks, where X is more than 2, and offers upto 1/X redundancy. > If more than 1 drive fails then your data is toast. This inherently allows > for data loss if more than only 1/3 or 1/4 (or less - 1/5 or 1/6 if you > have enough drives in your system) fail. > > RAID6 needs an extra disk over RAID5 (at least 4 total?), and allows 2/X of > them to fail whilst still maintaining data integrity. > > I guess that theoretically RAID6 might be more robust than RAID1 but > realistically one would probably use RAID1 if the volume is intended to be > a fixed size (system volume), RAID5 or RAID6 if you want to be able to > easily expand the volume (add an extra drive and store more data simply by > expanding the filesystem). Other kinds of RAID (10, 50 &c) may be more > suitable if read or write speed is also important for specialist > applications, but you say you're only interested in home workstation use, > not the datacentre. > > Note that I only consider hardware RAID - others may be able to give advice > more suited to Linux's software RAID. > > I use RAID5 for my TV recordings and DVD rips. There's a famous article > claiming RAID5 is worthless considering the size of current hard-drives vs > uncorrected error rates (which manufacturers express per million or > billion bits). I'm sceptical of the article, but nevertheless I guess I'm > starting to get paranoid enough I'd prefer RAID6. Unfortunately my > hardware RAID controller doesn't support it, so I guess I'm saved the > expense. :/ Useful info - many thanks! -- Rgds Peter