From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from archlinux.org (gerolde.archlinux.org [66.211.214.132]) by mail.saout.de (Postfix) with ESMTP for ; Fri, 4 Jun 2010 17:00:08 +0200 (CEST) Message-ID: <4C0914F5.4060001@archlinux.org> Date: Fri, 04 Jun 2010 17:00:05 +0200 From: =?ISO-8859-15?Q?Thomas_B=E4chler?= MIME-Version: 1.0 References: <4C052084.1030100@archlinux.org> In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------enigA5287E15D2EECA93845ED33E" Subject: Re: [dm-crypt] dm-crypt alignment + ssd + raid List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Cerfon Cc: dm-crypt , Milan Broz This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigA5287E15D2EECA93845ED33E Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Am 04.06.2010 14:31, schrieb Philippe Cerfon: >> The scenario dm-crypt->LVM is easier, as there is no extra layer betwe= en >> the LV and filesystem. >=20 > Well,... I rethought the whole thing. > I still think that RAID should be at the bottom, but then we can have e= ither: > a) disk-->RAID-->dm-crypt-->LVM-->fs > or > b) disk-->RAID-->LVM-->dm-crypt-->fs Yes, both are supported. > (a) seems to be more naturally, as LVM is (as you've said) directly > below the fs,.. but... if I now add new disk because I want to enlarge > the fs,... I'll end up in using at least different master keys, as > dm-crypt is below LVM, right? > This would be avoided with (b) as far as I understand. That is correct. I use the dm-crypt->LVM setup on laptops, where a second disk will never be added. If you expect the LVM to be split over several VGs, then a per-logical-volume encryption seems more logical. >>> 2) I guess at any of the levels from above, one can partition the >>> exported block device, right? >>> So e.g. partition the physical disks that each has one big sdX1, and >>> create the RAID on it _OR_ create the RAID directly on the disk >>> withoug partitioning. >> I wouldn't rely on partitions, LVM is way more flexible. > So what is suggested now? >=20 > I start e.g. with /dev/sd[a-d],... putting the RAID/MD directly on > sd[a-d] or on sd[a-d]1? If you boot from an external medium (as you say below), then I see no need to even partition the drives. Linux handles sd[a-d] (without partition table) just fine. > (I ask because this might have an effect on the alignment thingy) >=20 > Then the raid gives me the "raid-device" /dev/md0. As I want several > LUKS volumes on my RAID (all with different keys) I could now either > partition md0, or set up LVM, right? Then on top of the > partitions/volumes dm-crypt,... on top of this my filesystems. Yes. I don't know how well partitioned md0 is supported. I would prefer LVM in any case, because it is very flexible - in particular, it does not rely on a specific physical layout of the volumes. --------------enigA5287E15D2EECA93845ED33E Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEAREIAAYFAkwJFPUACgkQEda5KzHP/VDWUwCggR9Cc8ajyKHSzQRrC9Ix07S7 AxkAoKss6v9jYC08AgOOwJli9Ki38YD4 =KKO1 -----END PGP SIGNATURE----- --------------enigA5287E15D2EECA93845ED33E--