I have a 120GB SSD and a 1 TB HDD. I would like to dual boot Ubuntu alongside Windows 10. I installed Ubuntu on a partition of the HDD, but Windows 10 was installed on the SSD so using a boot manager wouldn't work and I'd have to change which drive to boot up in every time I start my computer. Is it possible for me to install Ubuntu on a small partition of my SSD, but only the actual OS itself, with all other data on the HDD?
Yes, it is possible, and supported.
The general way people split their installation is to put
/ (the root) on the smaller partition and
/home (where most of the data is stored) on a larger partition. However, you can also put just
/boot on the SSD and the rest of your OS on the HDD.
However*2, you can install Ubuntu completely on the HDD without worrying about split drives and double bootloaders and all that, which is what I recommend you do. When you install Ubuntu, it will install GRUB to the EFI partition on your primary hard drive, which should be the SSD. GRUB will be able to boot into both Ubuntu and the Windows bootloader, even if they are on separate drives. All you need to do is install Ubuntu, and it should configure everything for you.
I recommend choosing the
Something Else... option in setup when prompted and manually telling Ubuntu to install to the partition you want there. While in this setup, also make sure that the EFI partition is going to mount as
If you need any more details, comment, and I'll help out.