Ok here we go, This is fast Lamens terms ( you get it or forget it.).
Raid 0 = Stripping, This is performance and it is disatorous when it fails, 2 drives minimum the more the better, No they dont have to match but it can help, When set up you get a combo of the drives put together.
This is how it works, A file being copied to a drive is broken down into small peaces (as many as the strip size allows) then are sent to the drives sorted this becomes fast because, As one drive is working to save that strip the next strip is sent to the next, HD's are slow in the machanic area compared to the electronics connecting them.
eg... I tested my onboard Highpoint 370 on my Epox 8KTA3+Pro just to see if it works, Hooked up a Fuji 6gig UDMA66 and Quantum UDMA33, Both drives tested (Dont laugh it was only a test Im not using it.) 7megs a sec transfer each by themselves but in a raid 0 I got marks of 23 megs a sec, Thats 4x the speed. (these drives are old and are very slow compared to newer high rpm drives)
Raid 1 = Mirroring , This is more of a safety feature, requires minimum 2 drives and can be slow if the data is not handled by the controller correctly. Simple it make the same things on both drives, One goes bad the other has the same thing on it and nothing lost and its easy to get the mirroring going again when you get another drive to add back in.
Raid 0,1 = Stripping and mirroring sametime ( I can be confusing this with Raid 5 but I thought that was more complex) Can work with 2 drives but thats just stupid since it would be the same as Raid 1, so it takes a minimum of 3 drives and when a file is stripped the same strip is saved to 2 of the 3 drives eg strip #1 of a file is saved to drives 1 and 2 the next strip is sent to 2 and 3 then maybe 1 and 3 I think you get the picture, This by the way works best with 4 drives as only 2 drive can be open at the same time on different channels (IDE limitation), (SCSI raid can strip/mirror around 15 drives at the sametime)
Raid 5 (Hardware raid only , Can be a costly controller) This takes a minimum 3 drives and works the same as Raid 0-1 but insted of using Identical mirrored strips it changes the mirrored stripes into a checksum and stores them on all drives, This is faster and also uses alot less space on the drives, Very safe very fast and quick at recovering data. Hardware raid also uses less CPU power.
Hope this helps, Please correct me if Im wrong.