The final word on the subject: From Storagereview.com
			
			Is RAID 0 Really Worth It? 04 February 2003
At any given point in time, all one needs to do is look at topic list in the SR Discussion Community to see a frenzy of enthusiasts pursuing increased drive performance through striping, or RAID 0. Many readers are pouring lots of money into such equipment and spending a great deal of time and effort configuring their arrays.
Details on RAID 0 may be found in this section of the SR Reference Guide. Suffice it to say that with two drives, when properly configured, RAID 0 will offer double capacity and sequential transfer rate offered by the standalone drive; but is it truly double the capacity and double the performance?
Capacity will indeed double. Bear in mind however, that data striped across two drives is much more vulnerable to loss as a physical failure of either drive results in loss of data on both. If capacity is the goal, it is better to run the two drives as distinct units.
What about performance? This, we suspect, is the primary reason why so many users doggedly pursue the RAID 0 "holy grail." Why they do, however, isn't clear.
Theory states that RAID 0 doubles transfer rates, but what do transfer rates really do for performance in contemporary desktop machines? As we've stated many times in the past, not much. STR simply does not significantly impact performance in typical desktop applications. There are certain cases, of course, such as editing of streaming data, where STR has a substantial impact. For other uses, however, its influence is insignificant.
So what's a "real world" speed increase? If we were to judge by the posts in the SR Community, everyone uses their RAID arrays for the sole purpose of running the deplorable ATTO PowerTools's benchmark. ATTO measures sequential transfer rates; it does not report anything remotely close to application-level performance.
Still interested in seeing what kind of benefits an inexpensive yet properly configured RAID 0 array delivers? While formal, ongoing RAID tests currently fall outside the existing purview of SR, consider an array that we constructed in our third-generation testbed using a Promise FastTrak SX2000 in conjunction with a pair of 200 GB Maxtor DiamondMax Plus 9 drives. We've run StorageReview.com's Desktop DriveMarks to demonstrate what kind of application-level increases one may expect. Those who are unfamiliar with and those who doubt the veracity of the Desktop DriveMarks are strongly advised to re-read our methodology article to put these results in proper perspective.
StorageReview.com 1x 200 GB DM+9 2x 200 GB DM+9 RAID 0
IPEAK Average Read Service Time 13.2 ms 13.3 ms
WinBench 99 Outer Zone Transfer Rate 55.3 MB/sec 109.4 MB/sec
Inner Zone Transfer Rate 31.6 MB/sec 63.1 MB/sec
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
Unsurprisingly, the dual-drive RAID 0 solution delivers double the sequential transfer rate of a single unit. The SR Office, High-End, and Gaming DriveMarks, however, all climb by less than 10%. Also consider the fact that the RAID array boasts double the capacity of the single drive: as a result, some of that performance increase we see between the single drive and the RAID array simply comes from the larger capacity and resultant shorter actuator travel distances. Is this worth twice the cost plus the cost of the controller?
A notable exception arises within the SR Bootup DriveMark 2002. Windows XP tracks the order of requests during the boot process and does its best to reorder data found on a drive to facilitate sequential reads as a system starts up. Since the Bootup DriveMark 2002 trace was captured from a system that had been restarted and defragmented many times, this individual test likely reflects the transfer rate advantage that one achieves through RAID 0. Therefore, if the primary purpose of one's machine is to start Windows XP, RAID 0 offers overwhelming performance benefits .
Again, RAID 0 does have its advantages in a handful of key applications and uses where data files are huge and/or data requests are highly sequential in nature. Data requests are not highly sequential, however, in typical desktop productivity and gaming usage patterns, the most often cited in "Help me build my RAID 0!" posts.
The point? Don't assume RAID 0 offers increased performance for all or even most applications... and don't assume that transfer rates reflect application-level performance.
				
		
			
	