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 1Q8tEy-0002Vg-W7 for garchives@archives.gentoo.org; Sun, 10 Apr 2011 11:55:41 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 8C88FE01C9; Sun, 10 Apr 2011 11:53:43 +0000 (UTC) Received: from smtpout.karoo.kcom.com (smtpout.karoo.kcom.com [212.50.160.34]) by pigeon.gentoo.org (Postfix) with ESMTP id 32F33E01C9 for ; Sun, 10 Apr 2011 11:53:42 +0000 (UTC) X-IronPort-AV: E=Sophos;i="4.63,333,1299456000"; d="scan'208";a="502813377" Received: from 213-152-39-90.dsl.eclipse.net.uk (HELO compaq.stroller.uk.eu.org) ([213.152.39.90]) by smtpout.karoo.kcom.com with ESMTP; 10 Apr 2011 12:53:42 +0100 Received: from [192.168.1.100] (unknown [192.168.1.100]) by compaq.stroller.uk.eu.org (Postfix) with ESMTP id C16BC6C532 for ; Sun, 10 Apr 2011 12:53:39 +0100 (BST) Content-Type: text/plain; charset=us-ascii 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 (Apple Message framework v1084) Subject: Re: [gentoo-user] [OT] Disk recommendations? From: Stroller In-Reply-To: <201104100850.41768.peter@humphrey.ukfsn.org> Date: Sun, 10 Apr 2011 12:53:39 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: <1DE2A557-8514-43FD-8EF5-ECA09B9854EB@stellar.eclipse.co.uk> References: <201104092100.19783.peter@humphrey.ukfsn.org> <201104100850.41768.peter@humphrey.ukfsn.org> To: gentoo-user@lists.gentoo.org X-Mailer: Apple Mail (2.1084) X-Archives-Salt: X-Archives-Hash: c61ce3d2f983be6cb15506422bc968fc 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=20 > would accrue from switching from RAID-1 to RAID-5 or above? And, in = particular,=20 > 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).=20 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. :/ Stroller.