From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: very degraded RAID5, or increasing capacity by adding discs Date: Wed, 10 Oct 2007 07:52:41 +1000 Message-ID: <18187.63529.526020.305681@notabene.brown> References: <20071008211313.6cd8bbb5@absurd> <470A846B.9090805@sauce.co.nz> <20071009002550.12b9b26d@absurd> <20071009004636.112c886e@absurd> <18186.63033.185101.385806@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from Mr. James W. Laferriere on Tuesday October 9 Sender: linux-raid-owner@vger.kernel.org To: "Mr. James W. Laferriere" Cc: linux-raid maillist List-Id: linux-raid.ids On Tuesday October 9, babydr@baby-dragons.com wrote: > Hello Neil , > > On Tue, 9 Oct 2007, Neil Brown wrote: > > On Tuesday October 9, janek_listy@wp.pl wrote: > >> > >> Problems at step 4.: 'man mdadm' doesn't tell if it's possible to > >> grow an array to a degraded array (non existant disc). Is it possible? > > > > Why not experiment with loop devices on files and find out? > > > > But yes: you can grow to a degraded array providing you specify a > > --backup-file. > Is there an estimate of how large this file can get ? > It's probably a calculation based on disk & array parameters . > But I was unable to find a reference on it from the manpage . > > Tia , JimL I think: chunk-size * old-ndisks * new-ndisks * 2 + 1K It might be smaller than that, but it shouldn't be larger. NeilBrown