This work present an overview of the application of high resolution magneti
c read hack mapping within a functioning production disk drive. It is demon
strated how magnetic or mechanical media defects can be visualized and disc
riminated against each other and how track squeeze effects and servo patter
n layout/integrity can be studied. Examples are given where only the native
data signal is used for the analysis or how additional over writing is use
d to gain further information. Like in many other fields, the visualization
of specific features enhances and contributes to the understanding of unde
rlying mechanisms.