Ok I will try to explain. I will throw in som indexnumbers, that is not real, but will give you an idea of it.
First the basics:
Raid-0/Stripping. This it where you run 2, 3 or 4 discs as one bigger and faster disc.
Raid-1/mirroring. This is where you mirror your data from one disc to another. If you use the same number and type of discs on the (0) side, as on the (1) side, there is almost no diference in performance for your discs on the (0) side.
Remember the (1) discs will never add anything but data safety.
If you use an uneven number of discs (three) then the disc that is set for mirroring(1) will determine the write speed of your first two discs, wich you then have in Stripping mode(0)
So,with your 3 discs you have two options:
3 discs in raid-0. You get the full efect of all 3 discs. Read/Write = 300%
2 discs in raid-0. and the last mirroring them (the +1).Read=180-200%, Write100%
If you have bourght a fourth disc then:
2 sets of 2xRaid-0. The one mirroring (1) the other. Read/Write = 200%
4xraid-0. Read/write = 400% (if your controler can handle it. Some can't handle the amount of data, and provide less than actual 3x and 4x speed.)
My advise is this.
Make some regular Ghost backups. Go for 3xRaid-0. Do some testing. If you then think your controler can handle it (if it tripples(or close to it) the speed) then you can add the fourth disc, if you feal you need it. Remember the step from three to four discs, only has a theoretical extra relativ performance of 33.3% to add. ie. (300%-400%), and you are already way above any bottleneck in the system, so you might realisticaly seen not notise any big difference. And hey! 3xraid-0 is also extremely fast. You can almost compare the data transfer rate of souch a system to that of a solid state memory disc like Ramdisk or I-ram.
You might also want to wait a couple of days. I'm in the process of testing this:
The discs I'm testing, perform rather close to the raptors, so you would be abel to draw some comparisons.
You can follow the progress here: