Originally posted by: beatle
RAID 0 or 0+1 will NOT help your seek times. Only faster harddrives will, or SCSI (if doing non-sequential read/writes).
You keep saying that seek times are higher in RAID. In regards to pure RAID0, you are correct; you are limited by the seek time of the disks. However, in RAID1, 0+1, or 1+0 (and RAID5 in some situations), you can get average seek times lower than a single drive -- in fact, this is the primary benefit of RAID1 besides data protection. This is because the data is replicated across multiple drives, and the controllers are smart enough to have the disk already 'closest' to the desired block go and fetch that block. The same sort of thing is used in SCSI/SATA with command queueing (though that is for multiple reads/writes on a single disk).
RAID will help you if you're indexing a large file (as in Soundforge, which is disk based) but reading from your array and writing to it will be SLOWER than reading from one drive and writing to another on a different channel.
Assuming you have an adequate amount of bandwith going to the controller, you will not be choking your disks by doing read/write operations simultaneously any more than you would with a single drive. In some cases, two single drives on separate channels (or using two separate disk arrays) MAY work better than a RAID0 array for tasks like this. This is a situation where stripe size, etc. can influence results considerably.
Reliability is another concern, as your likelihood of losing data is roughly DOUBLE (well, not exactly double, for you statistics majors

). Please, if you're going to run RAID 0, PLAN for a failure, even if using reliable drives.
You should plan for a failure (ie, back up your data) whether or not you use RAID0. That said, drive failures are a fairly rare occurrence, and even at double the normal frequency I would not lose sleep over it unless this was a mission-critical machine. You're about 1.4x as likely to have a failure in a given time window in a RAID0 configuration.
My personal experience with RAID 0 wasn't all that great. After running it for a few months, I lost a drive and I went back to a single drive configuration. Much to my surprise, things didn't really seem slower.
The performance benefits of RAID on desktop systems are restricted mostly to a few specific types of applications -- anything that reads or writes large volumes of data, especially sequentially (such as video editing programs). If you do those sorts of things regularly, it's going to be noticeable. Otherwise, it's probably not doing enough to justify its extra cost.