From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 4E1151381F3 for ; Fri, 13 Sep 2013 23:17:31 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 11719E0D4D; Fri, 13 Sep 2013 23:17:27 +0000 (UTC) Received: from mail2.viabit.com (mail2.viabit.com [65.246.80.16]) (using TLSv1 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 0F435E0C3E for ; Fri, 13 Sep 2013 23:17:25 +0000 (UTC) Received: from [172.17.29.6] (vpn1.metro-data.com [65.213.236.242]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail2.viabit.com (Postfix) with ESMTPSA id 3ccCRn2yyfz1hgY for ; Fri, 13 Sep 2013 19:17:25 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=orlitzky.com; s=mail2; t=1379114245; bh=AEtpWrN6/LgEBcRBT8BnMIzHxBQgvJCc/SHv2gVP92o=; h=Date:From:To:Subject:References:In-Reply-To; b=KpNGBV+JSnvk/NNRgC6kvOj8kEVCVci6Z5Xg3e6ET/7IDEUKisXoxHlQDgmdF5Bfd s00oeDMWn6xoQ4jhPEQYVIsM4BZ8amoT2GgBAqDQuu0oEAvrKuJOoBmoHihgkIBi7B vS4ugyvY1jHCTE6eBbo0qDVQ5g6p8luVi8+4JikA= Message-ID: <52339D03.1000105@orlitzky.com> Date: Fri, 13 Sep 2013 19:17:23 -0400 From: Michael Orlitzky User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130909 Thunderbird/17.0.8 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 To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] {OT} Need a new server References: <5233792D.7040900@orlitzky.com> In-Reply-To: X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Archives-Salt: f4581d44-b06d-432a-8a9d-433a8e79dd2e X-Archives-Hash: a0fa24e01edae7059dec772814ddefc1 On 09/13/2013 05:47 PM, Grant wrote: > > I had no idea. How awesome. So the entire array shows up as /dev/sda > when using a real hardware controller? Just enable an extra kernel > config option or two and it works? > Yep. >> Yes. RAID10 both stripes and mirrors. So you can lose one, and it's >> definitely mirrored on another drive. Now you have three drives. If you >> lose another one, is it mirrored? Well, maybe, if you're lucky. There's >> a 2/3 chance that the second drive you lose will be one of the remaining >> mirror pair. >> >> Recommendation: add a hot spare to the system. > > Would the hot spare be in case I lose 2 drives at once? It's just to minimize the amount of time that you're running with a busted drive. The RAID controller will switch to the hot spare automatically without any human intervention, so you only have to keep your fingers crossed for e.g. 3 hours while the array rebuilds. This is as opposed to 3 hours + (however long it took the admin to notice that a drive has failed). > Isn't that extraordinarily unlikely? If the failures were random, yes, but they aren't -- they just seem that way. The drives that you use in a hardware RAID array should ideally be exactly the same size and have the same firmware. It's therefore not uncommon to wind up with a set of drives that all came off the same manufacturing line at around the same time. If there's a minor defect in a component, like say a solder joint that melts at too low of a temperature, then they're all much more likely to fail at around the same time as the first one. > Are modern SSDs reliable enough to negate the need for mirroring or do > they still crap out? I don't have any experience with SSDs, but a general principle: ignore what anyone says, mirror them anyway, and make lots of backups.