Your answer lies in the Powerquest website. Take a look at this article from the website.

I have already done this numerous times for earlier releases of Fedora w/o the default LVM setup. I can't see HDB as DeviceMapper only shows me a single "virtual" drive combining both HD's into one.
I have a networked FULL Backup of Disk 1 and it's a good thing I did because although I selected first sector of the boot Partition for GRUB (not MBR) upon re-boot all I saw were the words GRUB at DOS screen and the system hung there. Had to restore the entire drive from my backup.
How can I ensure GRUB goes on Disk 2 (HDB) when I can't see Disk 2 with DeviceMapper?

Thought I might add this. I'm writing this from Fedora Core 6. The trick was to install using the nodmraid option. With that enabled I could now see both SDA and SDB and all partitions in them. It was then a simple matter of loading GRUB to the boot partition of SDB instead of the MBR.
After going back and reviewing danleff's answer I retried installing Core 6. This time I got the following error message "Invalid partition table on /dev/mapper/nvidia_jchbhada --wrong signature ccc6.
My mobo is an MSINeo2Platinum. The BIOS has RAID disabled.
The trouble was not that I didn't know how to work with Boot Magic chainloading GRUB which in turn loads Fedora, it was with devicemapper not allowing to see my two SATA HD's. Instead it presented me with ONE HD by combining both at the Disk Druid screen. Thus I had no choice but to install GRUB on SDA (it did not give an option to install to SDB) as to devicemapper no SDB existed. Naturally since I now had GRUB and BootMagic both acting as Boot Loaders on the same MBR everything froze on bootup.
I wish the answer were as simple as danleff implied but until I applied nodmraid I couldn't see my 2 HD's.
I hope this clears up any confusion. As I posted previously the problem was not the bootloaders but devicemapper.

Nice detective work.
 
I think that the title of your thread threw me off and had me looking on another direction.
 
But the question that you posted on the first post should have clued me in.
 
I bet that there is a bios setting messing up the works and the nodmaraid option ignored the bios setting. I now seem to remember this before in a previous thread. Your last post also gave important information, namely the motherboard you were using, which has had some quirks with Linux installations.
 
But the result is the same, you were able to effectively troubleshoot the problem by working it through.
 
For an interesting read on the subject (of course on older Fedora installations) see this thread from the Fedora Forum.
 
 

Absolutely correct about the BIOS setting being ignored. It's linked to the RTL8169 ethernet. This board has two GB ethernets one an NVidia and the RTL8169.
Strangely when I enable the RTL ethernet I get a POST message NVIDIA RAID ROM BIOS vX.XX on startup then a "detecting arrays" message appears. This is despite the fact I have RAID DISABLED in the BIOS and there is no RAID array configured.
If I disable the RTL I receive no such message. I haven't the foggiest idea what the ethernet controller has to do with the RAID, but there is definitely a connection.
I have no doubt that this ethernet controller (the RTL 8169) is what is fooling devicemapper into thinking I have a RAID array enabled. That is what caused my whole problem in the first place.
So I went and disabled the RTL, re-booted and tried to re-install Fedora. Sure enough at the Disk Druid screen I could see both drives SDA and SDB. I'm sure if I would have gone further Grub and Fedora would have booted normally bootstrapping off Boot Magic.
So there are two options to make Fedora work with this board on installation. Use the nodmraid option or disable the RTL 8169. I opted for the first as at least I have both ethernets working.
Now if I could just figure out what a network controller has to do with the Hard Drives.

I got curious about this and looked around. This is after the fact, but look in the bios under sata devices configuration and note the two settings; (1) ATA/IDE Configuration and (2) Configure SATA as...
 
Note how the drives are being detected under both settings, by reading the users manual (online - english) on page 3-13.
 
Note that there are multiple modes that can be set in both settings, depending on what you have for hard drives.
 
(1) ATA/IDE Configuration = Compatible ???
 
(2) Configure SATA as...IDE????
 
 
This is assuming that you have the same board, model MS-7028 (v.1.0B). I bet the answer lies in these two settings.
 
I have a Biostar board, but remember having a hell of a time with this. I'll have to look at my settings.
 
Just some thoughts, but I like your solution. I'll have to remember this.
 
 

You're right. I disabled both IDE controllers (I have two SATA Drives not arrayed)When I do so the RTL ethernet controller does NOT show a RAID message. Both SATA drives are listed under IDE on the main BIOS page as the 3rd master and 4th master drives.
But I need to enable IDE to keep my DVD RW Drive accessible so now what? I only have it enabled on the primary controller. The secondary ide IS disabled. Maybe I should move it to the secondary controller? I don't think it will make any difference.
Again, what is the connection between an onboard ethernet controller and the storage system?

I'm having a problem booting up Mandrake Linux 2006. I'd installed it fine on my old machine, but on my new pc, after the initial installation, it freezes whenever i try to boot up linux (i'm currently having to use Windows XP Media Center Edition which came with my new machine :.S ).
 
Any suggestions would be appreciated
 
My machine is an Acer Aspire T180 : AMD Athlon64 X2 Dual Core, 1GB DDR2, 160GB SATA, NVIDIA GeForce 6100 nForce 405
 
I'm quite tired of Windows, and the sooner i can get into Linux the happier i'll most likely be
 
Again, thanks a lot for any help you could give me!
 
PS: i'm a bit of a linux noob