RAID 0: This level is usually set up to increase performance. Since it spreads the writing onto 2 or more disks, the writing speed is faster and each drive has to write less. It also combines all the drives. The thing with RAID 0 (and many other levels of RAID) is that if you have a 100 gb harddrive and a 120gb harddrive, the computer will see them as one 200 gb harddrive, not 220. This is because in order for RAID to function, it makes the drives equal. This level is not redundant
RAID 1:RAID 1 creates an exact copy (mirror) of all data writen to one disk onto 2 more or disks. This is commonly used on servers as a form of backing data up. Therefore anything written or deleted on 1 harddrive will be deleted/written on another. RAID 1 also increases performance even though you lose the use of the other harddrives. Since the computer provides sectors when looking to run a program, the search is split among the various harddrives, cutting seek times in half. To get the full redundancy benifits, use independent disk controllers (1 for each disk).
Those are some basics on RAID. Another thing is, most SATA drives are RAID ready, and I am not sure if IDE or PATA drives are able to run RAID.



