Single M.2 Boot with a Raid1 Mirror on standard HDD

I posted this over in the Mobo forum but wasn't getting much luck with responses, therefore, I was hoping maybe you guys would know more on this?

I previously had a Intel RST Raid1 array setup for my storage drives. A simple 1TB mirror. Tonight, after making sure the system was stable and the M.2 is performing as it should, I attempted to get my array setup again. I simply connected the two SATA drives and enabled RAID instead of AHCI in the BIOS.

The minute I did this, the array was visible and appeared to pick up right where it left off. However, at that point, I can no longer boot off of the M.2 drive. As a matter of a fact, the BIOS won't even see it. The minute I change everything back to AHCI, the M.2 comes back, but of course, my RAID array is non-existent.

Is there a secret combination of settings the enable the M.2 as a single boot drive and then the two SATA drives as RAID storage?

For what it's worth, I'm using M.2 slot 2, which is at the bottom of the board on an MSI Gaming M5 motherboard.

Any help is appreciated!

I would guess that the M.2 needs to be defined in whatever RAID config manager you have and is no longer being seen as a stand alone drive. If you do this you may lose all your data, I'm not familiar with that controller, or how it initializes a new drive. You should be able to look without making any changes though to see if this is indeed what's happening.

Thanks for the reply. The Mobo is using Intel RST...so do you think I need to set the mode to RAID and then reinstall Windows 10 on the M.2?

Did you see if the M.2 showed up in the RAID config as undefined? If this is the case you may need to define it and will probably need to reload the OS, possibly not, I can't be sure. but I certainly wouldn't make any changes unless you were prepared for that. Also, if you do need to reload the OS, you'll probably need your RAID driver available on a USB drive or something during install.

Now, it's possible I'm way off on all of this, so don't take my ramblings as gospel, but it seems reasonable and I've seen this before.

Figured it out! Found the solution by following the steps someone else used in Windows 10 to change from IDE to AHCI. The same worked for AHCI -> RAID. I'm not sure if I can link to that forum, so I'll just post the method from the author "toobad":

1. Run Command Prompt as Admin
2. Invoke a Safe Mode boot with the command: bcdedit /set {current} safeboot minimal
3. Restart the PC and enter your BIOS during bootup.
4. Change from IDE to AHCI mode then Save & Exit.
5. Windows 10 will launch in Safe Mode.
6. Right click the Window icon and select to run the Command Prompt in Admin mode from among the various options.
7. Cancel Safe Mode booting with the command: bcdedit /deletevalue {current} safeboot
8. Restart your PC once more and this time it will boot up normally but with AHCI mode activated.
9. Bask in the reflected glory of being a total Windows 10 God

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