I had quite the experience trying to change IDE disk mode in BIOS to AHCI.
After trying to update initramfs I some how lost the rockstor web ui (maybe related to removing a drive?).
I eventually had to reinstall Rockstor.
It seems many distros now always include AHCI support so it is a non issue if the interface type is changed from IDE to AHCI. But not Rockstor.
Please consider including AHCI support regardless of current disk mode.