From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wols Lists Subject: Re: 3-way mirror to RAID-6 Date: Tue, 26 Dec 2017 10:09:45 +0000 Message-ID: <5A421FE9.8000200@youngman.org.uk> References: <87incu79uw.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87incu79uw.fsf@notabene.neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown , Gandalf Corvotempesta , Linux RAID Mailing List List-Id: linux-raid.ids On 25/12/17 21:53, NeilBrown wrote: > On Mon, Dec 25 2017, Gandalf Corvotempesta wrote: > >> Hi to all >> I have a server with a 3way mirror. >> As I have to increase the total available space, one solution would be to >> replace all disks with bigger ones, but this is expensive. >> >> Another solution would be to add just one disk and then reshape from >> RAID-1 to RAID-6 >> >> Do you have any guide on how to do this reshape on a running array ? >> Thank you. > > I suggest you add the new device with "mdadm --add", then try the > reshape with "mdadm --grow /dev/mdXXX --level=6 --raid-devices-4". > > It might not work quite that easily - I think you need to first convert > the raid1 to a 2-way mirror, but that is easy enough > > mdadm --grow /dev/mdxxx --raid-devices=2 That was my reaction. I'm 99% certain that a three-way will not reshape. > > NeilBrown > Cheers, Wol