From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Robinson Subject: Re: max number of devices in raid6 array Date: Mon, 17 Aug 2009 17:06:55 +0100 Message-ID: <4A89801F.5050907@anonymous.org.uk> References: <20090812090600.GF21118@nfs-rbx.ovh.net> <55226.78.86.108.203.1250069920.squirrel@www.yuiop.co.uk> <20090812121911.GG21118@nfs-rbx.ovh.net> <87ab259j8m.fsf@frosties.localdomain> <60099.78.86.108.203.1250094780.squirrel@www.yuiop.co.uk> <87zla44e9a.fsf@frosties.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87zla44e9a.fsf@frosties.localdomain> Sender: linux-raid-owner@vger.kernel.org To: Goswin von Brederlow Cc: David Cure , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 13/08/2009 03:52, Goswin von Brederlow wrote: [...] > I would take that with a verry large pinch of salt. From the little > experience I have that value doesn't reflects reality. You're probably right, given that the data error rate hasn't dropped (it might have grown, given the higher areal densities, but in fact it's been about 1 in 10^15 for a while) while drive size has grown. While I was looking at the IDEMA LBA standard stuff, I found their paper about long sectors (also discussed here recently) which features a wee graph of hard drive capacity vs rebuilds before data loss in a 7-drive RAID-5 with 512-byte sectors, showing about 450 rebuilds for 36G drives but only 10 for 1.5T drives. See page 9: http://www.idema.org/_smartsite/modules/local/data_file/show_file.php?cmd=download&data_file_id=1779 Cheers, John.