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 1Nf85L-0004v5-U9 for garchives@archives.gentoo.org; Wed, 10 Feb 2010 08:38:12 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 636CAE0993; Wed, 10 Feb 2010 08:37:50 +0000 (UTC) Received: from mail-fx0-f216.google.com (mail-fx0-f216.google.com [209.85.220.216]) by pigeon.gentoo.org (Postfix) with ESMTP id 23803E0993 for ; Wed, 10 Feb 2010 08:37:50 +0000 (UTC) Received: by fxm8 with SMTP id 8so7834629fxm.26 for ; Wed, 10 Feb 2010 00:37:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:received:received:from:to:subject:date :user-agent:references:in-reply-to:mime-version:content-type :content-transfer-encoding:message-id; bh=nwkNAB/JO83f+Cb1diJ6vdkcClnMnXK5I1wfZRfevW0=; b=gswwiLfhWwHZZkZxKXSzRYAWHjEL/WMmVg4oNTjk4pQI1ov3DBHtgZkcxdOFevO7i3 Hj+IRKlZ7eVlSKPjiuFa1yESsglZbJq8ewf4yw3a7xwU2RCKbSpOXiI/5OFpHD4DRTox wvHmPe6ZSSD8cAU9IH/Te7Kxca8PeTnL1Pd4A= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=from:to:subject:date:user-agent:references:in-reply-to:mime-version :content-type:content-transfer-encoding:message-id; b=SZTT8vBkB8A9W7EHSDsGcrsV02XKaCHTmMArlCwfq5TnRHaJHLDIuDgr6D43/Ok5UR VueUyK+sf2w3Od3TuUw3KxqP4VFPY7PIvM+QMHboEtA+Y2JW7zEbL5LXzFKbDynzrQZ9 qy0kPhKlDAy4NbExKgxBNShMFwjo3rD6t/NY4= Received: by 10.102.14.13 with SMTP id 13mr865436mun.32.1265791068207; Wed, 10 Feb 2010 00:37:48 -0800 (PST) Received: from energy.localnet (ip-80-226-1-7.vodafone-net.de [80.226.1.7]) by mx.google.com with ESMTPS id u26sm5571506mug.7.2010.02.10.00.37.46 (version=TLSv1/SSLv3 cipher=RC4-MD5); Wed, 10 Feb 2010 00:37:46 -0800 (PST) From: Volker Armin Hemmann To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] 1-Terabyte drives - 4K sector sizes? -> bar performance so far Date: Wed, 10 Feb 2010 09:37:44 +0100 User-Agent: KMail/1.13.0 (Linux/2.6.31.12r4; KDE/4.3.95; x86_64; ; ) References: <5bdc1c8b1002070827i14f59047k39a695900ebe9889@mail.gmail.com> <201002100731.44737.volkerarmin@googlemail.com> <1265785907.3225.10.camel@localhost> In-Reply-To: <1265785907.3225.10.camel@localhost> 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: <201002100937.44717.volkerarmin@googlemail.com> X-Archives-Salt: 3fcc7481-9f56-4158-b8b5-50d94ec59584 X-Archives-Hash: 1360c935f1f749776bd635a8a407572d On Mittwoch 10 Februar 2010, Iain Buchanan wrote: > On Wed, 2010-02-10 at 07:31 +0100, Volker Armin Hemmann wrote: > > On Mittwoch 10 Februar 2010, Iain Buchanan wrote: > > > so long as you didn't have any non-detectable disk errors before > > > removing the disk, or any drive failure while one of the drives were > > > removed. And the deterioration in performance while each disk was > > > removed in turn might take more time than its worth. Of course RAID 1 > > > wouldn't suffer from this (with >2 disks)... > > > > Raid 6. Two disks can go down. > > not that I know enough about RAID to comment on this page, but you might > find it interesting: > http://www.baarf.com/ > specifically: > http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt and that is very wrong: but if the drive is going these will not last very long and will run out and SCSI does NOT report correctable errors back to the OS! Therefore you will not know the drive is becoming unstable until it is too late and there are no more replacement sectors and the drive begins to return garbage. [Note that the recently popular IDE/ATA drives do not (TMK) include bad sector remapping in their hardware so garbage is returned that much sooner.] so if the author is wrong on that, what is with the rest of his text? And why do you think Raid6 was created? With Raid6 one disk can fail and another return garbage and it is still able to recover. Another reason to use raid6 is the error rate. One bit per 10^16 sounds good - until you are fiddling with terabyte disks. >Conclusion? For safety and performance favor RAID10 first, RAID3 second, RAID4 third, and RAID5 last! and that is just mega stupid. You can google. Or just go straight to wikipedia, if you don't know why.