The encoding method of the disk refers primarily to the algorithm(s) used to
change user data into a pattern of bits that can be stored on the platters. This isn't
nearly as simple as it sounds; therefore, several different but related methods have been
developed over time to facilitate this conversion (and of course, subsequent conversion in
the other direction when the data is read back from the disk.)
Improved encoding methods have one main impact on hard disk performance: they increase recording density, and thus areal density. This improves positioning and
transfer performance as described in those sections. Encoding methods are discussed in
detail in this section; it contains a relevant
comparison between the different methods used over the years, showing how data density has
been increased as they have been improved.
Like hard disk read/write heads, encoding
method is rarely discussed in hard disk performance circles because it doesn't change very
often, and also because it doesn't vary greatly from one drive to the next. Mostly, its
effects are bound up in the areal density
specification, as well as the transfer rate specifications.
Next: Track and Sector Layout
