Method to accurately predict hard error rates resulting from encroachment

Abstract

A disk drive utilizes a unique write condition for each of the transducers within the drive. Each write condition is determined based upon the specific properties of the corresponding transducer. The write condition information is preferably stored within a memory within the disk drive. When a write operation is performed, the appropriate write condition for the corresponding transducer is used to determine when to write data to the disk. A write condition will typically include one or more individual write criteria. For example, a write condition can specify a write threshold value to be used during a write operation. A write fault threshold value is selected for each transducer by determining a position error distribution corresponding to that transducer wherein the position error distribution is essentially a function of random noise associated with the disk drive, and by using that distribution to determine allowable off-track threshold value (WFL), will protect the drive from encroachments.