Re: [gentoo-user] How to get raid

[Alexander Puchmayr]

On Wednesday 04 January 2012 11:57:18 Jeff Cranmer wrote:
> Hi all,
>
> I have recently built a new system, running Gentoo on a Sabertooth 990FX
> motherboard.  The board has a raid controller on which I'm running a
> 120GB solid state drive for the OS (Raid 0) and a set of three 1.5TB
> drives which were previously running as a RAID5 array.
>
> I can see the sda 120GB drive and have installed the operating system on
> that.  I can't see one device for the three disk RAID5 array, even
> though the RAID BIOS reports it as a healthy 3TB disk.  Instead I see
> three separate devices, sdb, sdc and sdd
>
> What do I need to do to mount the 3TB RAID disk?  I'm running genkernel,
> and compiled it with genkernel --dmraid all.  It should already have
> data on it, if I can only get gentoo to recognise it.
>
> I can see the RAID controller when I use lspci
>
> 00:11.0 RAID bus controller: ATI Technologies Inc SB7x0,SB8x0,SB9x0 SATA
> Controller [RAID5 mode] (rev 40)
>
> One possible clue may be in dmesg, where I get the error
> device-mapper: table: 253:0: raid45: unknown target type
>

The first question is: What type of raid are you using?

a) Software-Raid created with mdadm & co

b) Hardware-Controller based raid.

While in the first case you see all individual disks with their partitions and 
a /dev/mdX entry that actually contains the raid failsystem, the second one
shows only a /dev/sdX holding the final raid drive. 

Additionally, for the hardware based raid, you'll need a driver for the 
controller that supports the raid5. I think this is the configuration you're 
trying to run, since you mentioned that you created your raid in the RAID 
BIOS.

I'm not sure (I've never tried this) whether there is a driver for Linux 
supporting raid modes on board-embedded HW raid controllers.

    Alex