How do you disable BIOS RAID on SuperMicro X9SCL/X9SCM motherboard?

Question

I am trying to install SLES11 on a computer with a X9SCL/X9SCM SuperMicro motherboard. The BIOS version is 1.1a (9/28/2011).

The SATA controller configuration gives me the following choices:

• AHCI
• RAID (Intel or LSI)
• IDE
• Disabled

I have tried both AHCI and IDE and with both of them, when the SLES11 installer comes up, it says it sees a "BIOS RAID" disk that it wants to install onto. If I go to the Export screen in the installer, under "Hard Drives" it shows me /dev/mapper/ddf_some_long_string, /dev/sda, and /dev/sdb but says the latter two are in use.

Surely the BIOS RAID isn't non-disableable? Perhaps there's old BIOS RAID metadata on the drives and the kernel is seeing it and being confused by it?

Solution

This is a fakeraid controller. That means that in reality, it is a bog standard AHCI SATA controller that has special bios and Windows' drivers that implement software raid. Changing the bios setting between AHCI and RAID only changes the PCI Identifier of the hardware to cause Windows to load the standard AHCI driver, or the vendor specific fake raid driver instead. Linux recognizes either PCI ID as an AHCI controller and loads the AHCI driver. Hence why Linux does not care which of those settings you use.

The dmraid software package recognizes the raid metadata that the fake raid bios leaves on the disks and configures the Linux device-mapper raid driver to access the raid array. To stop this, you need to delete the raid metadata from the disks with either the bios raid utility, or by running the dmraid command with the -E switch to erase the metadata from a given disk.

Comments

[QuantumMechanic]

Makes a lot of sense! Any idea what do to, though, if dmraid -r -E /dev/sda errors out when it actually attempts to delete the metadata?

[psusi]

@QuantumMechanic, that would depend on what the error message says.

[QuantumMechanic]

We were never able to use dmraid to wipe the metadata. So though it took several hours, we used d-ban from dban.org to wipe the drives. That did the trick and the SLES11 installer no longer sees the bogus BIOS RAID volume. Even though we weren't able to do exactly what the answer said, the answer was dead-on on the reason for what was going on and therefore I'm accepting it. Thanks!