I have 3 hard drives, 2 of which I want to set them up as RAID. I understand that one of the RAID types (Do not know if it is RAID-0,1..6) improves performance by using 2 hard drives simultaneous. The 2 hard drives are identical. Same size and all. How can I set them up as RAID to improve performance on the Desktop Ubuntu (This is not a server but a home computer).
To get both a read and write performance boost, you would want to use RAID0 (stripe) or LVM. Basically, this allows multiple hard drives to seek and read and write at the same time. Note that there's no redundancy in this case, as there's no data replicated across devices.
If you used a RAID1 (mirror), you'd get a performance improvement on reads (as the data you're looking for can be read from each disk), but writes are more expensive because you have to write to both disks.
RAID5 and RAID6 provide some read advantages as data is striped, but are generally less performant due to high CPU requirements for calculating parity.
Hope that helps!
EDIT: The RAID has to be supported by Your mainboard to do so. On most mainboards You get simple options in BIOS to set RAID and such stuff. Good idea would be to read carefully mainboard manual to avoid possible problems with incompatibile BIOS settings.