Disk drive reducing write unsafe threshold when detecting an unrecoverable servo compensation value

A method of operating a disk drive comprising a disk comprising a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises servo data and a servo compensation value, and a head actuated over the disk, the method comprising:

• defining a plurality of data tracks relative to the servo tracks;
• and
• while servoing the head over a target data track during a first write operation:
• generating a position error signal (PES) at each servo sector based at least in part on the servo data;
• when the servo compensation value of a first servo sector is recoverable, aborting the first write operation when the PES generated at the first servo sector exceeds a first write unsafe threshold;
• when the servo compensation value of the first servo sector is unrecoverable, aborting the first write operation when the PES generated at the first servo sector exceeds a second write unsafe threshold less than the first write unsafe threshold;
• recovering the servo compensation value from at least two other servo sectors in the target data track;
• and
• generating the second write unsafe threshold based on the servo compensation values recovered from the at least two other servo sectors.

A disk drive comprising:

• a disk comprising a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises servo data and a servo compensation value;
• a head actuated over the disk;
• and
• control circuitry operable to:
• define a plurality of data tracks relative to the servo tracks;
• and
• while servoing the head over a target data track during a first write operation:
• generate a position error signal (PES) at each servo sector based at least in part on the servo data;
• when the servo compensation value of a first servo sector is recoverable, abort the first write operation when the PES generated at the first servo sector exceeds a first write unsafe threshold;
• when the servo compensation value of the first servo sector is unrecoverable, abort the first write operation when the PES generated at the first servo sector exceeds a second write unsafe threshold less than the first write unsafe threshold;
• regenerate the servo compensation value for at least one servo sector of the target data track based on the PES generated for each servo sector;
• and
• generate the second write unsafe threshold based on the regenerated servo compensation value.

A method of operating a disk drive comprising a disk comprising a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises servo data and a servo compensation value, and a head actuated over the disk, the method comprising:

• defining a plurality of data tracks relative to the servo tracks;
• and
• while servoing the head over a target data track during a first write operation:
• generating a position error signal (PES) at each servo sector based at least in part on the servo data;
• when the servo compensation value of a first servo sector is recoverable, aborting the first write operation when the PES generated at the first servo sector exceeds a first write unsafe threshold;
• when the servo compensation value of the first servo sector is unrecoverable, aborting the first write operation when the PES generated at the first servo sector exceeds a second write unsafe threshold less than the first write unsafe threshold;
• regenerating the servo compensation value for at least one servo sector of the target data track based on the PES generated for each servo sector;
• and
• generating the second write unsafe threshold based on the regenerated servo compensation value.