From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roger Heflin Subject: Re: Basic RAID5/6 reshape question Date: Thu, 11 Dec 2008 21:52:39 -0600 Message-ID: <4941E007.4090907@gmail.com> References: <4940E377.7070907@wasp.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4940E377.7070907@wasp.net.au> Sender: linux-raid-owner@vger.kernel.org To: Brad Campbell Cc: RAID Linux List-Id: linux-raid.ids Brad Campbell wrote: > G'day all, > > I'm just doing some system upgrades and shuffling some arrays around as > part of the process. > All my other current questions have been answered by experimentation, > but one. > > I'm going to start with a RAID 6 comprised of 7 x 1TB drives, and > reshaping to 10 x 1TB. > I'm doing an experiment right now with re-shaping a RAID-5 of 2 drives > into 3 drives which is taking about 20 hours, from that I'm assuming > that a nice big re-shape will take a considerable amount of time. I have > a reliable UPS, I'm more concerned about a drive or cable flaking out. > > What happens if I'm in the middle of a reshape of a RAID 5 or 6 and lose > a drive? > > Will the array be able to continue to reshape in a degraded state? > > Hoping of course that this does not occur, but just trying to plan ahead > in case. > > Regards, > Brad Reshaping appears to be much much slower. I can resync in just a 2-3 hours, but a reshape of a single drive takes 10-15 hours with nothing else happening, if any other work is being done by the disks the number gets much worse. To make it look just like a normally built array of the same number of disks it is very likely that reshaping is moving lots and lots of data around to make the changes. I have so far done 2 reshapes, and I would like to know also how dangerous an event would be if it happens during a reshape.