From mboxrd@z Thu Jan 1 00:00:00 1970 From: moft@fmailbox.com Subject: Re: growing a RAID-10 array with mdadm 3.3.1+ ? Date: Tue, 11 Oct 2016 11:37:17 -0700 Message-ID: <1476211037.1004490.752738017.68CF1E3E@webmail.messagingengine.com> References: <1476206815.989242.752665505.6525EE00@webmail.messagingengine.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Anthony Youngman , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Tue, Oct 11, 2016, at 11:29 AM, Anthony Youngman wrote: > Growing an array is pretty safe, but like anything here, it does have its dangers. > > Second, what distro are you running? Is it a systemd-based distro? Opensuse. Yes. > feeling is that systemd is "to blame". I have no idea why that'd be the case. That's the first time I've heard anybody suggest that. > > *CAN* I safely grow/expand it? > > Bugs excepted - yes you should be able to, without problems. So grouwing 'far' layouts are now supported? Do have a reference/source for that? > > This will always change data_offset, and will fail if there is no > > room for data_offset to be moved. So a 'fail' means -- just won't start? as opposed to 'oops, it's now broken'? > > So far I haven't found any specific "how to" for this process. > > mdadm /dev/md0 --add /dev/sde1 /dev/sdf1 > mdadm --grow /dev/md0 --raid-devices=6 > > The first command will add your two drives as spares. The second will > make them part of the array. It's the second command that's the risky > one... and bearing in mind I don't know raid10, it might just add them > on the end and not need any reconstruction at all ... Well, that's the missing critical detail here. > > (1) The changelog refers to 'near' and 'offset' layouts, but doesn't mention 'far'. > > > > CAN I safely grow this layout=f2 array ? > > > > (2) If I can, what's the detailed procedure to do it? Still need to understand the 'far' support, namely yes/no. > I'll be interested in knowing how this pans out, too, so I can add it to > the wiki :-) Thanks Mike