From mboxrd@z Thu Jan 1 00:00:00 1970 From: maurice Subject: Re: Looking for the best way to do this Date: Thu, 23 Jun 2011 16:06:19 -0600 Message-ID: <4E03B8DB.7010607@gmail.com> References: <4E00DF31.2020406@gmail.com> <4E03929A.8000503@cdf.toronto.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4E03929A.8000503@cdf.toronto.edu> Sender: linux-raid-owner@vger.kernel.org To: Iordan Iordanov Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 6/23/2011 1:23 PM, Iordan Iordanov wrote: > Hi Maurice, > > On 06/21/11 14:13, maurice wrote: >> Add 3rd disk to make a 3 disk RAID1 >> Make a RAID10, missing one disk. > > Perhaps I misunderstand your supposition, and if I do, please correct > me. RAID10 with mdadm does not require a minimum of 4 disks. Yes, that was my understanding. > For example, mdadm can do RAID10 with 2 copies on 3 disks or RAID10 > with 3 copies on 3 disks, yielding the equivalent of RAID1 in terms of > data security. It is not confined to mirroring two pairs of disks and > then striping across them as is the "conventional" way of doing RAID10. Yes, I understand the principle. > > You can read the man-page of mdadm, where the options for "layout" of > RAID10 are discussed. Pay particular attention to the end of the > "--layout" option explanation. What I do NOT know is the following: A) Which is more RELIABLE: R1 with 3 disks or R10 with 3 disks. B) HOW to create either the 3 disk R1 or R10, assuming an existing 2 disk R1. -- Cheers, Maurice Hilarius eMail: /mhilarius@gmail.com/