From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chase Venters Subject: Re: how to add third drive to RAID1 made of two drives without destroying data Date: Sat, 22 Oct 2005 13:18:59 -0500 Message-ID: <200510221319.22002.chase.venters@clientec.com> References: <1129999982.11518.18.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-6" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1129999982.11518.18.camel@localhost.localdomain> Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: Juraj Holtak Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Saturday 22 October 2005 11:52 am, Juraj Holtak wrote: > I know I can use the "new" drive I bought today as spare, but I really > miss the point of a spare for raid1. I think, it makes much more sense, > to build in the drive as a live one, so instead of RAID1 made of 2 > drives, I`ll get RAID1 made of 3 drives. > > I use mdadm to manage the drives. If I use --manage --add and add the > drive(partition) to the array, it becomes a spare disk and this is not > what I want it to do. > > Is there a way to upgrade my raid, without destroying data? Indeed. Check mdadm --grow: Usage: mdadm --grow device options This usage causes mdadm to attempt to reconfigure a running array. This is only possibly if the kernel being used supports a particular reconfiguration. This version only supports changing the number of devices in a RAID1, and changing the active size of all devices in a RAID1/4/5/6. Options that are valid with the grow (-G --grow) mode are: --size= -z : Change the active size of devices in an array. : This is useful if all devices have been replaced : with larger devices. --raid-disks= -n : Change the number of active devices in a RAID1 : array. I haven't done it before personally, but I'd imagine: mdadm --grow /dev/md0 --raid-disks=3 would be a good start (if not the total solution). Cheers, Chase