[Fixed] Hdd not found after installing Ubuntu (Alienware 15 Notebook)
I recently had a problem which I fixed by now, I'm just writing this here in case someone else might encounter the same issue.
My setup is an Alienware 15 notebook with a SSD and a HDD, which had windows already pre-installed on the SSD. I used the hdd solely for my files (music, vids etc.)
I installed Ubuntu 15.04 with an usb bootloader on the SSD. I didn't think much when the installer didn't show me the HDD at all, as I didn't want to install it there anyways, and made a small partition on the SSD for the ubuntu loader.
Problem encountered here, after I restarted the pc I though had both the Windows and the Ubuntu bootloader working successfully, though neither of them was able to find the HDD. Curiously even the BIOS itself couldn't detect the HDD and was only able to recognize the SSD on the second place.
Putting SATA mode to AHCI didn't change anything, and after I put it into ATA the system was no longer able to start as it crashed immediately at POST. It was obviously because I switched to ATA, sadly I couldn't reenter the BIOS to change it as it always crashed before.
Solution: I opened the system, removed the SSD and restarted. The HDD was now properly recognized, I was able to reset SATA mode back to that "Intel Rapid Storage" thing. Shut down PC again, reopen, reinstall SSD, restart pc and BAM, suddenly both drives were shown how they were before the Ubuntu installation. All my files and the installations are still intact and there seems to be not damage done gladly.
So, if you have the same issue with one drive not showing up in the BIOS or the BIOS even crashing in POST, try removing the other drive/the drive with the bootloaders.