AHCI and RAID for BIOS settings when using 2 or more SATA hard disk

Question

My third-hand desktop machine have the following BIOS settings:

At what scenario should I choose 'RAID' and what scenario should I choose 'AHCI' and what other scenario should I choose 'DISABLED'?

Solution

Choose Disabled or "IDE" mode only for compatability, which may include installing older operating systems, prior to the system having proper AHCI drivers installed (and set). To get boot when it will not boot any other way (because the drivers are not installed proper).

Optional: leave it on disabled if you just don't care :-) It will always boot if you install without AHCI.
Many bioses Default to "disabled" or "IDE" mode, so remember how it is set-up, if the bios settings are cleared the crasy thing will crash, and then you forgot why :-)

Choose the RAID option when you are going to create an array with more than one disk. When that array is created for the ICH controller via the raid bios. (not when using a software only raid).

Optional, you can still select RAID, and set up the drives as single or not at all, and drives will still work under the raid bios (and drivers) as singles. There is no reason to do this but it is well known that you can have an array created with more than one disk, and have loose singles still using that same settings and driver.

Choose AHCI in all other situations, when no array assembly will be made back in the hardware. Even via slightly older drive items. As long as the driver is set-up in the operating system even older drives will work using that method. AHCI features are especially faster for SSD drives, and to have full support of SSD features. It makes little differance in speed or responsiveness for the usual Hard Drives.
Hot Swap is also one of the features, although I never would recommend hot swapping when you do not need to.

Changing this with an installed windows operating system can (heck it Will) cause the system to flat out crash, very bad. It should not crash when changing from RAID to AHCI but it still can (raid setting is said to support achi). You must have the correct driver setup, either in a safe mode, or prior to changing the setting to get normal boot.

That just leaves "how to change from AHCI to IDE modes , and still being able to boot the system without crashing." That is covered all over the web, and here at SU somewhere also.

Comments

[Richie Frame]

I can confirm that AHCI features are available with the RAID setting, at least on ICH10R.