From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Landman Subject: Re: RAID 5 build time optimization question and experiments. Date: Fri, 11 Dec 2009 10:44:36 -0500 Message-ID: <4B2268E4.80905@scalableinformatics.com> References: <20091211152938.GA5857@cthulhu.home.robinhill.me.uk> Reply-To: landman@scalableinformatics.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20091211152938.GA5857@cthulhu.home.robinhill.me.uk> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Gsacapital! Robin Hill wrote: > On Fri Dec 11, 2009 at 02:55:31PM +0000, Cat'Killer wrote: > >> I found a way using Doug Gilbert's great sg3utils to zero all these >> disks in a very efficient manner, using sgp_dd, at near drive >> bandwidth, and proceeded to zero all the disks fully in about 4 hours! >> >> Once done, I then created a RAID 5 on 10 disks, waited for the rebuild >> to complete, stopped the array using mdadm, and dumped each of the >> RAID's components superblocks to files. >> > <-snip-> >> The create worked fine and I waited for the rebuild to be complete >> before stopping the array and dumping the SBs. >> >> I then proceeded to write these same superblocks to 10 new similar >> disks in a different system. >> > You could just do the create with --assume-clean, which should take very > little time at all. If the drives were zeroed initially then this will > give you valid parity data. > > Cheers, > Robin > -- Joseph Landman, Ph.D Founder and CEO Scalable Informatics Inc. email: landman@scalableinformatics.com web : http://scalableinformatics.com http://scalableinformatics.com/jackrabbit phone: +1 734 786 8423 x121 fax : +1 866 888 3112 cell : +1 734 612 4615