Onward to a 4 disk array then. Given what we saw with the 2 and 3 disk RAID 0 arrays, we're not likely to see significant performance increases.
With a four disk RAID 0 array, ATTO shows us:
Let’s see what HDTach has to say about the 3 disk RAID 0 set:
HDTach clearly shows the same performance at the start of the array, but now extends all the way to the end. 200MBps sustained no matter where on disk - which means we're now limited by the RAID controller not the disks. We managed 70MBps per disk with 3 disks; yet with 4 disks we manage only 50MBps each.
Should HDTune then, to see the difference between sequential and random access:
Here we see the same sequential performance as with 3 disks, except the performance does not drop off towards the end of the array.
Again, though, the bane of our results is in random IO - despite having data spread across 4 disks, the FiT can manage only the random IO of a single disk. Indeed - performance has perhaps dropped off a percentage point or two, perhaps indicating we are at the limits of either the RAID controller or our measurement methods.
