Why doesn't my RAID 0/1 work?

NOTE: This does not apply to every case, but does apply to SOME cases.

Depending on what controller is providing RAID, you may run into problems where your system will fail to boot. It can be confusing because you may see the bootloader and even select an option to boot, only to be met with a hung system.

In some cases, this can be due to using what is known as Fake RAID. This is an implementation of RAID 1 or 0 (Usually RAID 0) using the onboard SATA controller. Unfortunately, this does not, and has not really worked properly in Linux, let alone Ubuntu. There are some drivers out there that may make this work, but in general, onboard "RAID" devices should be avoided. If you need to do RAID, you should use a real hardware RAID controller, or software RAID if hardware controllers are not available.

Generally, you will find this sort of Fake RAID on desktop machines and low-end server systems (they generally use the same SATA controllers).