From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phil Turmel Subject: Re: Raid 5 to 6 migration Date: Fri, 01 Feb 2013 17:04:29 -0500 Message-ID: <510C3BED.2030408@turmel.org> References: <510C0075.9010908@turmel.org> <20130202001625.2b7d6514@natsu> <510C072B.1030108@turmel.org> <065BDBBE-7DB8-40CC-B1BC-8DCEE327F7C4@colorremedies.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <065BDBBE-7DB8-40CC-B1BC-8DCEE327F7C4@colorremedies.com> Sender: linux-raid-owner@vger.kernel.org To: Chris Murphy Cc: Roman Mamedov , linux-raid mailing list List-Id: linux-raid.ids On 02/01/2013 01:49 PM, Chris Murphy wrote: > > On Feb 1, 2013, at 11:19 AM, Phil Turmel wrote: > >> On 02/01/2013 01:16 PM, Roman Mamedov wrote: >>> >>> --layout=preserve will make it an order of magnitude faster. Read "man mdadm" >>> for more details. (And "man md" to learn about things in general.) >> >> But will leave the array "unbalanced"--the 7th drive will never be used >> for reads in normal (non-degraded) operation--reducing read performance. > > Does this option mean, in effect, the 7th disk is just a parity disk? So, sorta like a hybrid RAID 5/RAID4. Yes, with just the Q left on the 7th disk. The remainder of the array is the normal raid5 stripe. See the manpage for the layout "left-symmetric-6". Phil