This question bothers me for years now... If it is inappropriate here, a valid answer would point me to the perfect place.
As far as I know, striping is used in several storage situations to speed up transfer rates: multiple hdd's in one computer, chips inside of ssd's, dual/triple channel memory, and probably more, that I don't know.
Harddisks ususally have a number of platters inside. Usually 1 to 5. Sometimes they're used on both sides, which means there are up to 10 heads inside the hdd. But no matter what number of platters is inside, the transfer rates of harddisks is the same. Why?
The fact, that the heads and platters always share the same position does not count for me. The data could still be distributed between the platters, lets say one byte on each platter, of the stripe size of a regular RAID could be used as well.
What is the reason for not striping inside of harddisks, or if it is done, why is the transfer rate of a 2-platter disk not the double of a one-platter disk?