The defining performance-limiting characteristic of hard disks compared to the other
main "performance" components is the fact that they operate mechanically.
Consider the other components of the PC that have a fundamental impact on overall system
performance: processors, motherboards, system memory, video cards. They are all
solid-state--no moving parts--and as such much faster than the mechanical parts that make
up hard disks. That's why memory access times are in nanoseconds, for example, while hard
disk access times are in milliseconds--a million
times slower!
Since mechanical parts are largely what limit hard disk performance, that makes them
the most important factors affecting performance. This section takes a look at three of
these key mechanical design factors in more detail.
Next: Size and Number of Platter Surfaces
