RAID=Redundant Array of Inexpensive Disks. Originally, it was employed to provide safeguard against catastrophic disk failure by creating an arrangement whereby one or more disks worked together in a mirroring arrangement. If one dies you can replace it and rebuild the RAID array from the healthy one. Then someone discovered that you could create an arrangement whereby the disks didn't mirror each other but complemented each other in a synergistic way that enhanced performance and also created one large logical drive that is "x" number of times larger than the smallest drive in the array, with "x" representing the total number of drives in the array. This is called "striping". Great idea except it provides no safety net and multiplies the risk of drive failure. It only takes one drive to fail in a purely striped array in order to bork the whole array. If you have more than two drives you can combine striping and mirroring in order to have the best of both worlds, with some compromise on the performance side because of increased overhead.
Two drives in a striped array is designated as RAID 0. Technically speaking, this is not RAID because there is no redundancy but that's what they call it anyway. Two drives in a mirrored array is designated as RAID 1. If you are using more than two drives in an array then you have other RAID designations such as RAID 3, RAID 5, RAID 10, etc. Most motherboards are capable of doing RAID 0 and RAID 1 but the more sophisticated RAID arrays require a dedicated add on card to pull off and they are not cheap. RAID arrays can be hardware driven or software driven or some combo of both.
To do striped RAID with a minimal risk of failure suggests the use of NAS or Enterprise level hard drives which are made for this purpose. You should not use dissimilar hard drives in a RAID arrangement or you are asking for trouble real fast. So don't mix spinners and SSDs. Ideally, the drives should have identical specs.
