Xtal wrote:Forgive me if i'm wrong but wouldn't adding an extra platter increase the transfer speed by 50%? If I understand correctly a file does not reside on a single platter, rather it is split evenly between platters. By increasing the number of platters from 2 to 3, instead of 4 heads there are now 6 that can read/write simultaneously.
I felt this way for a while too. But a few weeks ago as I was doing research on an HD upgrade I came across the data sheet for the 7K200 series, available
here. As the specs reveal, the 200 GB version (2 high density platters) and 100 GB version (1 high density platter) have the same maximum media transfer rates. Similarly, the 160 GB version (2 lower density platters) and the 80 GB version (1 lower density platter) have the same maximum media transfer rates, in this case lower than the 200 & 100 GB versions. And the 120 GB version utilizes 2 platters of the same lower density as the 160 & 80 GB versions, but of presumably smaller platter size, thus achieving the same maximum media transfer rate as the 160 & 80 GB versions.
So it would appear that it is the
rotational speed and
areal density which determine transfer rates, not number of heads.
Another consideration is disk latencies. Higher transfer rates mean little in many contexts if access times are high, such as the case for the SpinPoint M6 320 GB version, because in real-world situations many small files are accessed from different locations.
Edit: For the OP, consider
this product, available soon. At 250 GB and 7200 RPM, I imagine it uses 2 x 125 GB platters, for a high rotation and higher density solution. This should be faster than existing 200 GB (2 x 100 GB platters) 7200 RPM HDs. And I'm sure other manufacturers, such as Seagate and Hitachi, will be announcing similar products soon. It's simply a question of how urgently you need the drive now, vs. how much you want the extra performance.