There are several guides for creating software RAID's on Ubuntu on the internet. Most of them we've found to be not very comprehensive or difficult to understand and follow. This is why we've created this tutorial as easy to use as we could. Pictures on every step and detailed instructions. In fact, it may be a little to comprehensive, but that's ok. At least you'll be confident you created the RAID correctly. If you do have any questions or run into a problem, feel free to leave a comment below and we'll try to help.
Linux software RAIDs work differently than normal hardware RAID's. They are partition based, instead of disk based. This means that you must create matching partitions on all disks before creating the RAID. Hardware RAIDs have you add the disks to the RAID and then create the partition.
This tutorial was created while installing Ubuntu 12.04 64 bit Server Edition. It's intended to be the first in a series of Linux software RAID tutorials. Future tutorials will cover topics such as how to recover from a failed disk.
This server has two 16GB disks installed. We will be creating 2 partitions: a 2GB swap partition and a 14GB root partition. After we are done, the server will stay in operation if one of the two disks fails. Most of the pictures in this tutorial are self-explanatory. The option you need to choose will be highlighted. We will provide comments on the picture if there is any special considerations.