Abstract: Disk drives with servo systems are described that include a servo ID pattern (SID) with a SAM field, as well as, one or more Integrated Servo sequences designed to provide a redundant sync mark function. The write-to-read gaps are omitted before selected servo sector SIDs. For example, write-to-read gaps can be omitted before alternating servo sector SIDs. When in write-mode that allows writing an extended user data sector without a write-to-read gap, the servo system delays the servo gate assertion with respect to the following SID to accommodate the absence of the write-to-read gap, which means that the SAM field cannot be read, but the Integrated Servo sequence(s) can be read and detected by the digital filters. Embodiments of the invention include sync mark timing for each SID (not just every other SID) even when writing extended user data sectors by using the Integrated Servo sequences to provide a sync timing function.