Does multi-platter hard-drive use all of their heads to read simultaneously?

To read or write all heads at once would require duplicating all the circuitry involved - head amplifiers, bitstream decoders, even the microprocessors and cache memory. I don't know how disks are actually designed, but it seems unlikely to me, especially given the price pressures in the industry. Besides, even the stream from a single platter is likely to be near the interface limit - it's the seeking and rotational delays that kill you.

I think that's already how it works :


A cylinder comprises the same track number on each platter, spanning all such tracks across each platter surface that is able to store data (without regard to whether or not the track is "bad"). Thus, it is a three-dimensional structure. Any track comprising part of a specific cylinder can be written to and read from while the actuator assembly remains stationary, and one way in which hard drive manufacturers have increased drive access speed has been by increasing the number of platters which can be read at the same time.


this quote from Wikipedia don't say it all, the guys from clearly say :

Only one head can read from or write to the hard disk at a given time. Special circuitry is used to control which head is active at any given time.

so this is for the low/middle-end HDD, BUT I came across few OLD discussions here and here where they are referring to the technique you are describing as "internal RAID" and I actually don't know enough about today's HDD technology.


Hard Drive