From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mari.romanrm.net ([157.7.203.202]:39466 "EHLO mari.romanrm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752077AbaF1KN7 (ORCPT ); Sat, 28 Jun 2014 06:13:59 -0400 Date: Sat, 28 Jun 2014 16:13:47 +0600 From: Roman Mamedov To: Duncan <1i5t5.duncan@cox.net> Cc: linux-btrfs@vger.kernel.org Subject: Re: RAID1 3+ drives Message-ID: <20140628161347.2097d308@natsu> In-Reply-To: References: <10572318.CAuhDIAMDU@xev> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/fOD8gEmvktAyLQJysyHs9O0"; protocol="application/pgp-signature" Sender: linux-btrfs-owner@vger.kernel.org List-ID: --Sig_/fOD8gEmvktAyLQJysyHs9O0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Sat, 28 Jun 2014 04:26:43 +0000 (UTC) Duncan <1i5t5.duncan@cox.net> wrote: > Russell Coker posted on Sat, 28 Jun 2014 10:51:00 +1000 as excerpted: >=20 > > On Fri, 27 Jun 2014 20:30:32 Zack Coffey wrote: > >> Can I get more protection by using more than 2 drives? > >>=20 > >> I had an onboard RAID a few years back that would let me use RAID1 > >> across up to 4 drives. > >>=20 > > Currently the only RAID level that fully works in BTRFS is RAID-1 with > > data on 2 disks. >=20 > Not /quite/ correct. Raid0 works, but of course that isn't exactly=20 > "RAID" as it's not "redundant". And raid10 works. But that's simply=20 > raid0 over raid1. So depending on whether you consider raid0 actually=20 > "RAID" or not, which in turn depends on how strict you are with the=20 > "redundant" part, there is or is not more than btrfs raid1 working. Also depending on what you consider "fully works", RAID1 may not qualify to= o, as neither the read-balancing, nor write-submission algorithms are ready for production use, performance-wise. (RAID1 writes to two disks sequentially, not at the same time; and reads are satisfied from in effect a random device, not from the least-busy device). --=20 With respect, Roman --Sig_/fOD8gEmvktAyLQJysyHs9O0 Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAlOulVsACgkQTLKSvz+PZwh3/gCaAkvqrCaZMgyoqiOVF7aRr0xj ZA8Ani/NeUPukO98T8vHvZxnwNcFLzD6 =45JM -----END PGP SIGNATURE----- --Sig_/fOD8gEmvktAyLQJysyHs9O0--