# US 9,437,240 B1 · Write encroachment mitigation system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,240 B1 - Document ID: US9437240B1 - Status: Granted - Kind: B1 - Application number: 14/719,052 - Filed: 2015-05-21 - Granted: 2016-09-06 - Earliest claimed: 2015-05-21 - Assignees: Seagate Technology LLC - Applicants: Seagate Technology LLC - Inventors: Quinn J. Haddock - Web page: https://patentgrep.com/patent/US9437240B1 ## CPC - G11B 20/10212: {compensation for data shift, e.g. pulse-crowding effects} - G06F 3/0619: {in relation to data integrity, e.g. data losses, bit errors} - G06F 3/0653: {Monitoring storage devices or systems} - G06F 3/0656: {Data buffering arrangements} - G06F 3/0676: {Magnetic disk device} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract The disclosed technology provides for a method and system comprising determining a write-encroachment threshold of a recording medium as a percentage of cross-track width of tracks in the recording medium, determining a track as off-track based on a position error signal level for the track exceeding the write-encroachment threshold, flagging one or more tracks substantially near the off-track, and writing write data for the one or more flagged tracks to a media cache. In a recovery process, the write data can be later transferred back to the flagged tracks. ## Claims ### Claim 1 A method comprising: determining a write-encroachment threshold (WET) of a recording medium as a percentage of cross-track width of tracks in the recording medium; determining a track as off-track and one or more tracks substantially near the off-track as unwriteable based on a position error signal (PES) level for the track exceeding the WET; flagging the one or more tracks substantially near the off-track track; and writing write data for the one or more flagged tracks to a media cache. ### Claim 2 (depends on 1) The method of claim 1, wherein the WET is between an on-cylinder limit and reported maximum and minimum PES levels. ### Claim 3 (depends on 1) The method of claim 1, further comprising transferring the write data from the media cache back to the flagged tracks when the media cache is full. ### Claim 4 (depends on 3) The method of claim 3, wherein transferring the data from the media cache back to the flagged tracks further comprises reading all the data from the media cache and then writing the data from the media cache sequentially. ### Claim 5 (depends on 4) The method of claim 4, further comprising clearing flags on the flagged tracks after the transferring operation. ### Claim 6 (depends on 1) The method of claim 1, wherein the flagged tracks are adjacent to the off-track in the direction of the outer diameter of the recording medium. ### Claim 7 (depends on 1) The method of claim 1, wherein the flagged tracks are adjacent to the off-track in the direction of the inner diameter of the recording medium. ### Claim 8 (depends on 1) The method of claim 1, wherein the flagged tracks are adjacent to the off-track in the direction of the inner diameter and adjacent to the off-track in the direction of the inner diameter of the recording medium. ### Claim 9 A storage device system, comprising: a memory configured to store data on data tracks; and a processor configured to determine a write-encroachment threshold (WET) of a recording medium as a percentage of cross-track width of tracks in the recording medium, determine a track as off-track and one or more tracks substantially near the off-track as unwriteable based on a position error signal (PES) level for the track exceeding the WET, flag the one or more tracks substantially near the off-track track, and write write data for the one or more flagged tracks to a media cache. ### Claim 10 (depends on 9) The storage device of claim 9, wherein the processor is further configured to write requests to the media cache when a write request is made to the flagged tracks. ### Claim 11 (depends on 10) The storage device of claim 10, wherein the processor is further configured to transfer the data from the media cache to the flagged tracks when the media cache is full. ### Claim 12 (depends on 11) The storage device of claim 11, wherein the processor is further configured to read data from the media cache and then write the data from the flagged tracks from the media cache sequentially. ### Claim 13 (depends on 12) The storage device of claim 12, wherein the processor is further configured to clear flags on the flagged data tracks when the data is written on the flagged tracks. ### Claim 14 (depends on 9) The storage device of claim 9, wherein the flagged tracks are adjacent to the off-track in the direction of the outer diameter of the storage medium. ### Claim 15 (depends on 9) The storage device of claim 9, wherein the flagged tracks are adjacent to the off-track in the direction of the inner diameter of the storage medium. ### Claim 16 (depends on 9) The storage device of claim 9, wherein the flagged tracks are adjacent to the off-track track in the direction of the inner diameter and adjacent the off-track in the direction of the inner diameter of the storage medium. ### Claim 17 (depends on 9) The storage device of claim 9, wherein the recording medium is shingled magnetic recording data. ### Claim 18 (depends on 9) The storage device of claim 9, wherein the WET is between an on-cylinder limit and reported maximum and minimum PES levels. ### Claim 19 A method comprising: determining a write-encroachment threshold (WET) of a recording medium as a percentage of cross-track width of tracks in the recording medium; determining a track as off-track and one or more tracks substantially near the off-track as unwriteable based on a position error signal (PES) level for the track exceeding the WET; flagging the one or more tracks substantially near the off-track track; writing write data for the one or more flagged tracks to a media cache; recovering the write data from the media cache during idle time; and writing the recovered write data to the flagged tracks. ### Claim 20 (depends on 19) The method of claim 19, further comprising determining a +WET and a −WET and determining off-track tracks exceeding the +WET and the −WET.