So, I have an older desktop I wanted to use as a file and print server for the household and decided to set it up with a simple 2 disk Raid 1. This means the 2 hard drives are mirrored. You can have one hard drive completely fail and lose no data at all. This is perfect for a little light duty file server. This is a bit slower than a one drive system, but that is not important because I am mostly concerned that I don't lose any data from the past 20 years.
I started by connecting 2 identical 300 gigabyte IDE hard drives that I already had in a ~8 year old computer. An old computer should work fine for this sort of thing...no need to spend any money at all.
You can follow the Ubuntu website documentation for setting up the Raid at installation time like I did at...
I setup identical boot and swap partitions on these two identical hard drives, and then created two Raid devices to mirror the respective partitions (md0 & md1). It is quite amazing that you can do all of this at installation time and the drives just start to sink up seamlessly in the background.
sda1 - /boot
sda5 - /swap
sdb1 - /boot
sdb5 - /swap
Once you have the Software raid setup, you can use the mdadm software to manage it.
sudo mdadm --query --detail /dev/md0