From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1RVSJx-0003TV-1y for garchives@archives.gentoo.org; Tue, 29 Nov 2011 18:22:22 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 6511F21C136; Tue, 29 Nov 2011 18:22:07 +0000 (UTC) Received: from out4.smtp.messagingengine.com (out4.smtp.messagingengine.com [66.111.4.28]) by pigeon.gentoo.org (Postfix) with ESMTP id 3F2C921C11A for ; Tue, 29 Nov 2011 18:20:48 +0000 (UTC) Received: from compute3.internal (compute3.nyi.mail.srv.osa [10.202.2.43]) by gateway1.nyi.mail.srv.osa (Postfix) with ESMTP id EAB4B23EA5 for ; Tue, 29 Nov 2011 13:20:47 -0500 (EST) Received: from frontend2.nyi.mail.srv.osa ([10.202.2.161]) by compute3.internal (MEProxy); Tue, 29 Nov 2011 13:20:47 -0500 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=binarywings.net; h=message-id:date:from:mime-version:to:subject:references :in-reply-to:content-type; s=mesmtp; bh=nNfQArrgLa79fi5hoj9xQ3sS YHA=; b=KRZzq6bsFbHylllF0ZAivRAO5YbyfQeh8ddfNsDC538BZK9RSokj7auz mPAnnDEwymzMMKmjd+jUM6J7DVcDhDJM3xeLyfUVNWqcwx8zJRjijh8Wkcrdsj5T DquNXLJRN0WIz4D6s6tqZpeFDsHBX27W+QeaFAbD33SkmuHWMOs= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=message-id:date:from:mime-version:to :subject:references:in-reply-to:content-type; s=smtpout; bh=nNfQ ArrgLa79fi5hoj9xQ3sSYHA=; b=I4tWFkO408BjwWLKp8vdXYE9IFL9AT1WrQwg X3Njs2OjdIwuzcXSPCiMSyoxAqw/gjxb5DULtrgG9CEidgl5tigzY8gd3x9hPSZt +rN/hguasQW6XaMi3+m0N/YChcMPMS/cZqQ+ENCYPprR9m3SbrQE7JtOFNzYcHLD iVO5UmY= X-Sasl-enc: u/E7CzOuNWQX33fSyzuW8DlxkPABX4TrI8+AO3AYGqpT 1322590846 Received: from [192.168.5.18] (serv.binarywings.net [83.169.5.6]) by mail.messagingengine.com (Postfix) with ESMTPSA id 66623482524 for ; Tue, 29 Nov 2011 13:20:46 -0500 (EST) Message-ID: <4ED52277.4060304@binarywings.net> Date: Tue, 29 Nov 2011 19:20:39 +0100 From: Florian Philipp User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20111031 Thunderbird/7.0.1 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] dmraid, mdraid, lvm, btrfs, what? References: <4ED484B5.4030700@binarywings.net> In-Reply-To: X-Enigmail-Version: 1.4a1pre Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigD38697E57417048B621B3925" X-Archives-Salt: 12e338db-9b04-4fa8-9556-86e5eab2435f X-Archives-Hash: 6d86682c32cfa782b1166b3696f12409 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigD38697E57417048B621B3925 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Am 29.11.2011 14:44, schrieb Michael Mol: > On Tue, Nov 29, 2011 at 2:07 AM, Florian Philipp wrote: >> Am 29.11.2011 05:10, schrieb Michael Mol: >>> I've got four 750GB drives in addition to the installed system drive.= >>> >>> I'd like to aggregate them and split them into a few volumes. My firs= t >>> inclination would be to raid them and drop lvm on top. I know lvm we= ll >>> enough, but I don't remember md that well. >>> >>> Since I don't recall md well, and this isn't urgent, I figure I can l= ook >>> at the options. >>> >>> The obvious ones appear tobe mdraid, dmraid and btrfs. I'm not sure I= 'm >>> interested in btrfs until it's got a fsck that will repair errors, bu= t >>> I'm looking forward to it once it's ready. >>> >>> Any options I missed? What are the advantages and disadvantages? >>> >>> ZZ >>> >> >> Sounds good so far. Of course, you only need mdraid OR dmraid (md >> recommended). >=20 > dmraid looks rather new on the block. Or, at least, I've been more > aware of md than dm over the years. What's its purpose, as compared to > dmraid? Why is mdraid recommended over it? > dmraid being new? Not really. Anyway: Under the hood, md and dm use the exactly same code in the kernel. They just provide different interfaces. mdraid is a linux-specific software RAID implemented on top of ordinary single-disk disk controllers. It works like a charm and any Linux system with any disk controller can work with it (if you ever change your hardware). dmraid provides a "fake-RAID": A software RAID with support of (or rather, under control of) a cheap on-board RAID controller. Performance-wise, it usually doesn't provide any kind of advantage because the kernel driver still has to do all the heavy lifting (therefore it uses the same code base as mdraid). Its most important disadvantage is that it binds you to the vendor of the chipset who determines the on-disk layout. Apparently, this gets better in the last few years because of some pretty major consolidations on the chipset market. It might be helpful if you consider dual-booting Windows on the same RAID (both systems ought to use the same disk layout by means of their respective drivers). >> What kind of RAID level do you want to use, 10 or 5? You >> can also split it: Use a smaller RAID 10 for performance-critical >> partitions like /usr and the more space-efficient RAID 5 for bulk like= >> videos. You can handle this with one LVM volume group consisting of tw= o >> physical volumes. Then you can decide on a per-logical-volume basis >> where it should allocate space and also migrate LVs between the two PV= s. >=20 > Since I've got four disks for the pool, I was thinking raid10 with lvm > on top, and a single lvm pv above that. > Yeah, that would also be my recommendation. But if storage efficiency is more relevant, RAID-5 with 4 disks brings you 750GB more usable storage. --------------enigD38697E57417048B621B3925 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk7VInsACgkQqs4uOUlOuU87YACeNwjpp7Lme24J8j9iOmD5NuY/ oc8AniCOx09j0QINOegZq+pca9LbGi2/ =99w9 -----END PGP SIGNATURE----- --------------enigD38697E57417048B621B3925--