2 drives in a RAID 0 is theoretically twice the performance of a single drive because when it writes to the drives, it will spread the data across both drives at once. The speed is just theory. Actual performance will very. There are limiting factors of the system that can affect actual performance.. Such as PCI bus speed and actual drive transfer speed. You will see more speed improvement from a RAID 0 than from a single SATA drive but don't get your hopes up as what you may expect from any benchmark program. When you see drives rated at 150MB/s, this is max transfer speed and not physical sustained data transfer speed. Normally with 2 SATA drives in a RAID 0 aarrangement you may expect about 80 or 90 MB/sec. Which is still about 30-40MB/sec more than what you would see in a single drive arrangement.
RAID controllers that are built into the southbridge of the MB chipset will offer the best performance because they are not limited to the bandwith of the PCI bus.
Some of the cautionary notes to heed by when implementing a RAID 0 array. ALWAYS BACKUP DATA. If you kept data on the array back it up often. If one drive fails you WILL lose all your data on the array. Since the time I have implemented my RAID array (which is a little over a year and a half now), I have had 3 drive failures. That is 3 different drives at 3 different times. The more drives you have in the array, the more chance of failure. I cannot stress this enough, BACKUP OFTEN.
