From mboxrd@z Thu Jan 1 00:00:00 1970 From: Changsen Xu Subject: Re: mdadm: which device set as source to mirror? Date: Sun, 11 Sep 2005 18:07:09 -0500 Message-ID: <1126480029.5932.6.camel@r40> References: <1126458858.6042.6.camel@r40> <17188.44497.481437.390441@cse.unsw.edu.au> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <17188.44497.481437.390441@cse.unsw.edu.au> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown , linux-raid@vger.kernel.org List-Id: linux-raid.ids Thanks for your quick response. It won't matter if I want to use 2 blank partitions to build RAID1; But now I wish to use mdadm to backup my /home partition, which already has tons of files on it; If mdadm happens to choose the other blank partition as source to do mirroring, all my data on /home will be lost; Hardware RAID always allows me to choose which partition/drive to be used as source. Regards, On Mon, 2005-09-12 at 08:21 +1000, Neil Brown wrote: > On Sunday September 11, xucs007@yahoo.com wrote: > > Dear Neil Brown, > > > > I'm trying to learn how to use your great mdadm, > > one thing I'm not quite sure, and couldn't find > > any clue in your man page, is, > > > > During create or assemble mode, for RAID1, which > > device mdadm uses as source to make the mirroring? > > Is there any differences to determine it > > for situations of same-size devices and different-size > > devices (>1% differences) ? > > I think it copies from the smallest numbered working drive (i.e. drive > 0 if that is working, else drive 1, etc). However it really > shouldn't matter to you. If you are doing something that depends on > having the right answer to this, you are probably doing it the wrong > way. > > If you would like to discuss it further, I suggest explaining what you > want to do, and why you think you need to know this, to > linux-raid@vger.kernel.org. > > NeilBrown > -- Changsen Xu