From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Bill Rugolsky Jr." Subject: Re: Adding larger disks to RAID5 Date: Mon, 21 May 2007 19:57:35 -0400 Message-ID: <20070521235735.GA26776@ti88.telemetry-investments.com> References: <465204AA.90301@dhp.com> <18002.11374.159035.143026@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <18002.11374.159035.143026@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: Christian , linux-raid@vger.kernel.org List-Id: linux-raid.ids Neil, What seems desirable to me is a way to take a new (larger) spare drive and add it to a RAID1 for a particular RAID 4/5/6 component, and then when it's sync'd, replace the now redundant small drive with another larger drive. Wash, rinse, repeat. This way the array is never degraded. Though I imagine that this particular arrangement doesn't have the benefit of the stripe rewrite when encountering a latent error on the drive that is being migrated. [Presumably the failing addresses could be cycled through the check from userland though, by doing a read above the stacked RAID.] One could start a RAID 4/5/6 array over a degraded RAID1 for each component, (i.e., a degraded RAID1). I haven't been following the metadata changes closely. Is it possible to do this with external MD metadata? It can also be done with device-mapper, but dm-mirror is very immature compared to MD RAID1. Comments? Regards, Bill Rugolsky