Servo sectors having multiple servo address marks in a data storage device

A method comprising:

• actuating a head over a storage medium for reading a plurality of servo tracks, wherein:
• the storage medium comprises a plurality of angularly spaced servo sectors defining the plurality of servo tracks and corresponding data sectors between consecutive servo sectors;
• and
• each servo sector is comprised of servo patterns corresponding to different servo tracks and comprising:
• a track identifier;
• a set of position error bursts;
• a first servo address mark preceding the track identifier;
• and
• a second servo address mark following the track identifier;
• selectively switching, based on a servo operating mode, between the first servo address mark and the second servo address mark for determining symbol timing for processing the servo pattern;
• positioning the head based on a read signal from the servo pattern and the determined symbol timing;
• writing, responsive to the servo operating mode being a data write mode, data to a target data sector preceding a corresponding servo sector;
• switching from a write element of the head to a read element of the head while the read element is positioned over the track identifier, wherein a relative position of the read element to the write element in a down track direction determines a read-write separation for switching;
• and
• reading, responsive to switching to the read element, the second servo address mark.

A data storage device comprising:

• a storage medium comprising a plurality of angularly spaced servo sectors defining a plurality of servo tracks and corresponding data sectors between consecutive servo sectors, wherein each servo sector is comprised of servo patterns corresponding to different servo tracks and comprising:
• a track identifier;
• a set of position error bursts;
• a first servo address mark preceding the track identifier;
• and
• a second servo address mark following the track identifier;
• a head actuated over the storage medium for reading the plurality of angularly spaced servo sectors;
• means for selectively switching, based on a servo operating mode, between the first servo address mark and the second servo address mark for determining symbol timing for processing the servo pattern;
• means for using, responsive to determining that the servo operating mode is a track follow mode, the second servo address mark to determine symbol timing for processing the set of position error bursts;
• and
• means for using, responsive to determining that the servo operating mode is another servo operating mode, the first servo address mark to determine symbol timing for processing the track identifier and the set of position error bursts.