I want to run my Debian install in AHCI mode on my computer. It runs perfectly fine, all drivers etc work perfectly also. The computer itself is in RAID mode but with all 4 RAID channels disabled (I refuse to use any RAID arrays because I simply don't like them). However, my computer (Acer Aspire m3640/m5640, motherboard MCP73PV/630i) has greyed out the option for me to change the option from RAID mode to either IDE or AHCI. Since I do not use RAID at all, I want to change to AHCI but it is greyed out in the BIOS. This option wasn't greyed out before as far as I remember.

I also have Vista x64 installed on a SATA drive along with Debian all partitioned. I also have an empty IDE drive attached which will be used for another operating system AFTER I have changed to AHCI mode. The SATA drive has the boot flag. I use GRUB to boot the operating system. My BIOS version from American Megatrends is R01-A3 (not the latest one, but the one I need to use).

My question is this, how could one possibly go about as to changing it to AHCI mode from RAID with the BIOS greying the option out. Or if not possible, how to make the BIOS ungrey the option (if there is another option preventing it from being changed or if the harddrives need configuring etc). I am not particularly concerned if the drives need to be wiped.

Thanks, Liam

Does vista have a striped volume partitioned in disk management? if so, you are running raid0. You have to have any raid functions disabled to switch to ahci or IDE.

If everything's working, though, there's no reason to switch unless you need IDE mode, or plan on changing to an older motherboard without RAID support and wish to preserve the data, which I find quite unlikely. Raid mode acts much like ahci with extra features. It will work exactly like ahci since you haven't installed any raid arrays. Performance, functionality or reliability won't be affected.

I have no striped volumes in disk management. All of my disks are simple partitions. All of my RAID channels are disabled therefore I see no reason why RAID0 (or RAID1) would even be functioning. I am really stuck as to why it is greyed out in the BIOS.

This computer comes with a recovery partition on the SATA disk, may this be a problem?

I want to use AHCI for my own benchmarking purposes and also to test out the "hot plugging" feature which appeals to me.

Thanks for replying,
Liam

As far as I'm aware, RAID Mode supports hotplugging, as long as you don't do it with RAIDed drives.

The recovery partition might have something to do with it, or maybe the BIOS is messed up. If you feel up to it, try removing the CMOS battery while the computer is unplugged (beware, all BIOS settings will be lost) and see if that fixes the option.

Most of the intel pages say that you set ahci by selecting raid. Amd boards may have achi as a single option.

I doubt it matters much unless you want to use hot swap.

I disconnected all hard disks and dvd drives connected to the computer and then booted up the BIOS. The option was still greyed out.

IF AHCI is the same as RAID, I may consider using IDE emulation mode but then again, the problem is I can't change the option to do so. Might there be a different way to enable IDE mode for my SATA drives? I really hate using RAID mode for my hard drives..

Thanks for the replies,
Liam

So, have you tried physically removing the CMOS battery yet? It should be in plain sight on the Motherboard. Removing it will lose your RTC (clock) data and your boot order (HD, CD, USB) but your hard drives should be unaffected. That should reset the options, hopefully restoring the AHCI and IDE options

IDE mode doesn't support hotplugging. Honestly, the only reason to ever use hotplugging IMO is for external hard drives. Opening up the computer case while it's running just to insert one drive and remove another doesn't seem like such a good idea. You could fry something else.

I have just removed the CMOS battery (whilst inplugged) and it indeed reset all the settings that were in my BIOS. Everything apart from RAID mode that is.

I understand that there is no benefit in using IDE/AHCI rather than RAID, however, it would save me a lot of trouble when using software that doesn't support RAID when RAID is disabled.

I would like to use IDE mode as nearly all operating systems are capable of using IDE as opposed to the problems seen by using a RAID array etc. Is there anything else I could try?

I don't know.....this is a longshot, but if you're desperate you could try unplugging the drives...perhaps they stopped the BIOS from switching back. If it frees it when the HD is unplugged, then you'll have to reformat the drive while it's in AHCI (i think, it might still work though)

The main disadvantage to IDE mode: SLOW at 150MB/s compared to up to 6.0 GB/s