From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Hill Subject: Re: What's the typical RAID10 setup? Date: Mon, 31 Jan 2011 10:14:09 +0000 Message-ID: <20110131101409.GA7861@cthulhu.home.robinhill.me.uk> References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="HcAYCG3uE/tztfnV" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Linux-RAID List-Id: linux-raid.ids --HcAYCG3uE/tztfnV Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon Jan 31, 2011 at 09:41:43AM +0000, Mathias Bur=E9n wrote: > Hi, >=20 > RAID10 is (could be) setup in this way, correct? >=20 > 2 devices in a RAID1 > 2 devices in another RAID1 >=20 > Then you run RAID0 on top of them. If you're lucky you can lose 2 > devices at most (1 in each RAID1). >=20 It could be, yes, or you could just use the RAID10 mode in md, which simplifies the process and offers you a selection of different physical layouts (some of which can offer significant performance benefits, depending on usage). > If you have, say 6 HDDs, would you create 3 RAID1 volumes? Then create > a RAID0 on top of them? >=20 Yes. > How would one go about expanding a 4 HDD RAID10 into a 6 HDD RAID10? > Is it "just" a matter of creating a new RAID1 array of the 2 new HDDs, > then adding them to the RAID0, then expanding whatever is on that > (lvm, xfs, ext4)? >=20 Expansion of RAID0 (or RAID10) is not currently implemented, though there is a workaround for RAID0. The basic steps are to convert to RAID4 with missing parity disk, expand, then convert back to RAID0. It's a bit more complex though as you need to prevent md from recovering the RAID4 array first - the full command process was posted a few days ago though, so a dig through the archives should find them. Proper RAID0 expansion should be in a forthcoming (next?) mdadm release, not sure about RAID10 expansion though. Otherwise, yes, those are the correct steps needed for expanding the array and filesystem. Cheers, Robin --=20 ___ =20 ( ' } | Robin Hill | / / ) | Little Jim says .... | // !! | "He fallen in de water !!" | --HcAYCG3uE/tztfnV Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (GNU/Linux) iEYEARECAAYFAk1Gi3AACgkQShxCyD40xBJJiwCfTaikinBYDfd2E/sBQUGd072c J1sAn0B+QiK/2ahrEJCf8C7+W4Y9VrLq =+n/x -----END PGP SIGNATURE----- --HcAYCG3uE/tztfnV--