From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Mamedov Subject: Re: wish for Linux MD mirrored raid types Date: Fri, 6 May 2011 15:50:59 +0600 Message-ID: <20110506155059.6f82cbeb@natsu> References: <20110506071752.GA22063@www2.open-std.org> <20110506133159.30c66519@natsu> <20110506090345.GA22245@www2.open-std.org> <4DC3BDD9.1060300@abpni.co.uk> <20110506094102.GC22245@www2.open-std.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/Q=8NX3dn1t6pOwUNcO9Cj_W"; protocol="application/pgp-signature" Return-path: In-Reply-To: <20110506094102.GC22245@www2.open-std.org> Sender: linux-raid-owner@vger.kernel.org To: Keld =?UTF-8?B?SsO4cm4=?= Simonsen Cc: Jonathan Tripathy , linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/Q=8NX3dn1t6pOwUNcO9Cj_W Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Fri, 6 May 2011 11:41:02 +0200 Keld J=C3=B8rn Simonsen wrote: =20 > > RAID1 is traditionally a mirror only setup (ok, some RAID=20 > > implementations may do some load-balancing of some sort). So a RAID1=20 > > with 4 disks is one data set copied onto 4 disks. Bandwidth is roughly= =20 > > the same as a single disk (ignoring any load balancing). > > RAID10 is mirror and stripe. A RAID10 with 4 disks is similar to a 2=20 > > disk RAID0 (double bandwidth with data split in half across both disks)= ,=20 > > but with each disk having a mirror (which brings the total up to 4 driv= es). > >=20 > > Additionally, a RAID1 disk (at least using MD) can be accessed just lik= e=20 > > a normal disk (good for recovery etc.) however a single disk out of a=20 > > RAID10 array is next to useless. >=20 > I think you are demonstrating some of my points about general knowledge > quite nicely. Don't worry, you are not alone. So what is your proposal: people do not know they can do X, but commonly do= Y, so let's rename X to Y so that both things are called Y and they 'know how = to do it'? RAID10 is an established term and means "stripe of mirrors", period. RAID1 means just a mirror. All the rest is just implementation details. Trying to redefine 2x2 to be 5 as some 'educational project' is definitely misguided. --=20 With respect, Roman --Sig_/Q=8NX3dn1t6pOwUNcO9Cj_W Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEUEARECAAYFAk3DxIMACgkQTLKSvz+PZwjZHgCfYGbfNcjIBLiaYThnYp6iUHuz l4wAljHAtFX8gzE9eLcNcOJiG+wEL90= =sVXK -----END PGP SIGNATURE----- --Sig_/Q=8NX3dn1t6pOwUNcO9Cj_W--