Ubuntu community is straight up about the fact that in the last few years, a number of hardware products have come onto the market claiming to be IDE or SATA RAID controllers. These have shown up in a number of desktop/workstation motherboards. Virtually none of these are true hardware RAID controllers. Instead, they are simply multi-channel disk controllers combined with special BIOS configuration options and software drivers to assist the OS in performing RAID operations. This gives the appearance of a hardware RAID, because the RAID configuration is done using a BIOS setup screen, and the operating system can be booted from the RAID.
If I read it in the news or just while browsing the net, I would not even pay attention, but…
Recently I had to setup a RAID5 on one of the P5 ASUS motherboard on Ubuntu Intrepid with 4 hard drives, 1 TB each . Let me tell you – it seems very “straight up” (like a shot of stoli), but it really is NOT..
Motherboards, like ASUS would claim to have a controller where you can configure a single RAID volume in the BIOS at the “Hardware” level. That is exactly what I tried at first, cause that just makes sense, right?
Well, it appears that this Asus RAID is not in any way “hardware”, therefore Ubuntu installation, sees all 4 drives instead of a single volume, as it should have, in case of a true hardware RAID controller.
So when Intrepid tries to create a Software RAID, out of these 4 drives, it fails, due to the reason that one layer of software RAID is already there – created by Asus.
To solve the problem Asus Raid configuration needed to be wiped out, and the “RAID” option in BIOS for SATA/SCSI should be disabled. Only then Software RAID can be manually created in Ubuntu. Manually, means answer “no” to “Activate Serial ATA RAID devices?” question, and go partition them away manually:
(just an example of a random Ubuntu install screen while configuring RAID1)
Then choose “Configure software RAID”, and create all the multidisk devices (“Create MD device”) from available volumes.
And watch out “that RAID is fake!”. Make sure you do enough research beforehand, to really make sure that the motherboard/controller that has a “Hardware RAID” support in specifications does in reality goes to the metal.
Good luck!