From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Zhang Subject: Re: how to clone a disk Date: Sat, 11 Mar 2006 19:36:07 -0500 Message-ID: <1142123767.27020.57.camel@localhost.localdomain> References: <1142038562.20484.234.camel@localhost.localdomain> <1142114892.27020.7.camel@localhost.localdomain> <1142122974.27020.43.camel@localhost.localdomain> Reply-To: mingz@ele.uri.edu 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: dean gaudet Cc: "Paul M." , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Sat, 2006-03-11 at 16:31 -0800, dean gaudet wrote: > On Sat, 11 Mar 2006, Ming Zhang wrote: > > > On Sat, 2006-03-11 at 16:15 -0800, dean gaudet wrote: > > > > > you're planning to do this while the array is online? that's not safe... > > > unless it's a read-only array... > > > > what i plan to do is to pull out the disk (which is ok now but going to > > die), so raid5 will degrade with 1 disk fail and no spare disk here, > > then do ddresue to a new disk which will have same uuid and everything, > > then put it back, then bitmap will shine here right? > > > > so raid5 is still online while that disk is not part of raid5 now. and > > no diskio on it at all. so do not think i need an atomic operation here. > > if you fail the disk from the array, or boot without the failing disk, > then the event counter in the other superblocks will be updated... and the > removed/failed disk will no longer be considered an up to date > component... so after doing the ddrescue you'd need to reassemble the > raid5. i'm not sure you can convince md to use the bitmap in this case -- > i'm just not familiar enough with it. i am little confused here. then what the purpose of that bitmap for? is not that bitmap is for a component temporarily out of place and thus out of sync a bit? > > > this raid5 over raid1 way sounds interesting. worthy trying. > > let us know how it goes :) i've considered doing this a few times > myself... but i've been too conservative and just taken the system down to > single user to do the ddrescue with the raid offline entirely. sure. after we finish this discussion and sort out a stable plan. do not want to risk my data. :P > > -dean