While trying to find out why my Intel RAID had disappeared after upgrading to Windows 10 (but I still had the disks visible), I was trying to install Intel RST to be able to configure my RAID and see if there was any configuration left. The Intel RST installer did however refuse to install, and just gave the cryptic message “This platform is not supported”. It didn’t say .. which platform or what a platform was or .. anything usable (and the log file didn’t tell me much more).
The reason? My motherboard had the SATA mode set to ACHI and not to “RAID”. Went into the bios, changed AHCI to RAID in the advanced / SATA configuration, and rebooted. Intel RST installed as it should! And I had to recreate my RAID1 – but Intel RST allows you to say “this is the disk you should keep, so mirror this to the other disk” when creating (be sure to check the LUN/BUS/etc. IDs in the properties for each disk so you can provide the correct disk as the master copy if they’re out of sync).
So: BIOS -> Advanced -> SATA -> SATA MODE -> RAID.