On Wednesday 17 May 2006 12:47, Peter Humphrey wrote: > Well, I tried the Software-RAID-HOWTO, and used a SuSE 9.3 DVD I had > lying around to create /dev/md0 to /dev/md5 on the /dev/sd[ab] disks > that are attached to the SATA interface. SuSE installed just fine and > is happy to run on these devices. > > In spite of that, when I boot the Gentoo 2006.0 installation CD and > tell it: > > gentoo dodmraid dmraid=-ay > > It says in the boot sequence: > > Activating Device-Mapper RAID(s) > No RAID disks > > Then when the image has booted, I say fdisk -l and I see the > partitions on /dev/sda and /dev/sdb with no trace of /dev/mdX. > > What am I doing wrong? > > Meanwhile I'll have a play with your scripts, Robert, and see if that > gets me anywhere - thanks.
This used to confuse me as well - from what I understand, MD raid (the one you set up with SuSE) and DM raid (the one you are trying to use with gentoo) are very different beasts. MD raid is the classic plain software raid (the one you set up using the software-raid howto), while DM raid (aka ataraid, biosraid, bios-assisted raid, and other similar names) uses the device mapper and is used mainly to be able to use raid volumes (often created under windows) that lie on disks attached to firmware-raid cards. These cards come with drivers (usually windows-only and proprietary) that emulate a hw-raid, so that windows can see the array as a single drive. Nevertheless, it's still an emulated (in software+firmware) hw-raid, meaning that a real os (like linux) will see the single physical drives, unless some kind of workaround (like DMraid) is in place, and even then I would not put my valuable data on it. That's why I (and others as well) suggest using plain MD software raid. See here: http://people.redhat.com/~heinzm/sw/dmraid/readme and, for the gentoo part http://tienstra4.flatnet.tudelft.nl/~gerte/gen2dmraid/ (read the "What can I do with the LiveCD / dmraid?" section) Hope this helps. -- [email protected] mailing list
