please help question about raid(URGENT)

i currently have 2 500gb wd re2s and a 36gb raptor, and i just orderd a raptor 150gb. i would like to know if it would be better to buy another raptor and put it in raid 0 or another 500gb re2 and put the three of them in raid 5. which one would give me the highest transfer rates? data storage is of no issue, i only want raid 5 because it stripes across 3 drives. i will be using this for gaming.

Details on RAID 0 may be found in this section of the SR Reference Guide. There are many misunderstandings based on the fact that with an even number of drives, when properly configured, RAID 0 will offer the combined capacity of all drives and almost the combined sequential transfer rate of all drives. This assumes that all drives in the array are identical. If this is not the case, each drive will generally be treated as if it is the same size as the smallest drive in the array, and the same speed as the slowest drive.

What about performance? This, we suspect, is the primary reason why so many users doggedly pursue the RAID 0 "holy grail." This inevitably leads to dissapointment by those that notice little or no performance gain.

One other example of a situation where RAID 0 might improve performance substantially is in certain games. Usually, first person shooters are not part of this list.
So, how do you tell what games might benefit significantly? It isn''t easy unless you have some knowledge of how the game works internally. For example, Interplay's "Baldur's Gate" series, as well as games based on the same engine (Planescape: Torment, Icewind Dale to name a few) benefit from RAID 0 because the levels that they load are essentially huge bitmaps. Because the hard drive is reading one large data file in a linear fashion (as opposed to the heads having to move rapidly back and forth to access many different files), sequential transfer rate is all but the only factor effecting loading speeds. Some other games benefit to a lesser degree.

As stated above, first person shooters rarely benefit from RAID 0.__ Frame rates will almost certainly not improve, as they are determined by your video card and processor above all else. In fact, theoretically your FPS frame rate may decrease, since many low-cost RAID controllers (anything made by Highpoint at the tiem of this writing, and most cards from Promise) implement RAID in software, so the process of splitting and combining data across your drives is done by your CPU, which could better be utilized by your game. That said, the CPU overhead of RAID0 is minimal on high-performance processors.

SR Office DriveMark 2002 395 IO/sec 426 IO/sec
SR High-End DriveMark 2002 373 IO/sec 408 IO/sec
SR Bootup DriveMark 2002 288 IO/sec 474 IO/sec
SR Gaming DriveMark 2002 519 IO/sec 529 IO/sec (1.9%)

Finally, it is sometimes beneficial to use the identical drives individually rather than in a RAID array because it is then possible for each drive to individually serve a different process. For example, one drive could handle paging to disk, and the other could handle other disk I/O needed by applications. Using a media example, one drive could read audio/video and the other could write the modified result. This would be faster than having a RAID array do both reads and writes, because individual drives could read/write linearly, eliminating the need to move the actuators back and forth between the area of disk being written to and the area being read from.

To summarize, RAID 0 offers generally minimal performance gains, significantly increased risk of data loss, and greater cost. That said, it offers the ability to have one large partition using the combined space of your identical drives, and there are situations where the benefit of the benefits outweight the disadvantages.

RAID 5 doesn't stripe across 3 drives. It will stripe the data across two drives and store parity information on the third.

In the interest of accuracy, I think you're wrong. I think RAID4 is a two stripe+parity, and RAID5 is actually a three (at least)-drive stripe