From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: LVM over RAID, or plain disks? A:"Yes" = best of both worlds? Date: Tue, 30 Nov 2010 11:42:57 +1100 Message-ID: <20101130114257.01134d62@notabene.brown> References: <2D.98.07087.690A2FC4@cdptpa-omtalb.mail.rr.com> <20101129152916.GB13310@www2.open-std.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: hansbkk@gmail.com Cc: Keld =?ISO-8859-1?B?Svhybg==?= Simonsen , Leslie Rhorer , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Mon, 29 Nov 2010 23:00:19 +0700 hansbkk@gmail.com wrote: > 2010/11/29 Keld J=F8rn Simonsen : > >> I can see how RAID6 is simpler than RAID10, but compared to RAID1? > > > > Hmm, does not compute by me. RAID1 and RAID10 are the same in compl= exity, > > RAID10 is just a modern RAID1, and should actually have been called > > RAID1. >=20 > My understanding is that if I use RAID10 on a single pair of disks > then that is literally the same as RAID1. These to me are very simple > in that I can take either one of the pair and mount it on any normal > machine and get at the data without doing anything special. >=20 > However, if I have my six disks configured as a single RAID10 array, = I > believe this is no longer true - the data from (at least the larger > of) the files has been distributed over all six disks, correct? >=20 > Now compare putting LVM on top of this array, compared to three RAID1 > pairs on the one hand and a RAID6 array on the other (third) hand :) >=20 > If I were trying to recover the data using the latest version of a > LiveCD - say Fedora or Knoppix, which would be easier? >=20 > I'm not trying to score any points, it's a genuine question. If you are comparing recovering after some sort of problem with a RAID10 over 6 devices compared with LVM over 2 2-device RAID1s, then= the former is certainly easier. This is simply because there are less laye= rs of complexity where something could go wrong. In both cases, your data will be spread across multiple disks, and any = one disk or even any two disks would be of no use to you. NeilBrown -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html