From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Another RAID level migration question Date: Fri, 10 Aug 2007 11:55:45 +1000 Message-ID: <18107.50593.330335.913673@notabene.brown> References: <46BB8B32.9010007@tmr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from Bill Davidsen on Thursday August 9 Sender: linux-raid-owner@vger.kernel.org To: Bill Davidsen Cc: Linux RAID List-Id: linux-raid.ids On Thursday August 9, davidsen@tmr.com wrote: > I have an array on two drives which was set up as a RAID-0, because I > needed the space and performance. Now I have another identical drive, > ideally I would like to get to RAID-5, but I don't think that is going > to fly, so how about RAID-4? I could create with a missing parity drive, > then add the drive and see if it will rebuild. > > I hope to test this using loop devices, but time is fairly short right now. Providing the two drives are exactly the same size (which rounded down to a multiple of 64K), this will work. The parity drive is the last in the list so mdadm -C /dev/mdX -l4 -n3 -c WHATEVER /dev/sda1 /dev/sdb1 missing is the sort of thing you want. NeilBrown