From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ram Ramesh Subject: Re: Raid5 to raid6 reshape or recreate? Date: Wed, 13 Aug 2014 23:10:16 -0500 Message-ID: <53EC36A8.7090308@gmail.com> References: <53EAB9F1.5030905@gmail.com> <53EC2D0E.2070402@fnarfbargle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53EC2D0E.2070402@fnarfbargle.com> Sender: linux-raid-owner@vger.kernel.org To: Brad Campbell Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 08/13/2014 10:29 PM, Brad Campbell wrote: > On 14/08/14 01:25, Ram Ramesh wrote: > >> On a slightly different topic, will it be faster after a disk >> fail/replacement as opposed to raid reshaping? > > Much. > I just re-striped a RAID6 changing the chunk size from 128k to 64k. > This took 12 days all up. It's the seeking that kills it. To replace a > disk or do a resync on the same array takes less than 10 hours. > > > I am curious. Why do you have to change chunk size? What is the benefit/advantage? This seem to confirm the --layout switch Neil Brown talked about. I need to find that switch. I have one more 3disk-raid5 to 4disk-raid6 reshaping to be done on another machine. I am going to do the --layout switch and do it in two steps. I suspect it will take about 10 hours with minimal seek. Ramesh