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Researchers Submit Patent Application, "Variable Stopwrite Threshold", for Approval

September 2, 2014

By a News Reporter-Staff News Editor at Information Technology Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventor Judd, Kevin B. (Tucson, AZ), filed on April 18, 2014, was made available online on August 21, 2014.

The patent's assignee is International Business Machines Corporation.

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to data storage systems, and more particularly, this invention relates to systems and methods for adjusting a stopwrite threshold when recording data on a medium.

"In magnetic storage systems, data is read from and written onto magnetic recording media utilizing magnetic transducers commonly. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. Read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.

"An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track and linear bit density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.

"In a tape drive system, magnetic tape is moved over the surface of the tape head at high speed. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial so that the recording gaps of the transducers, which are the source of the magnetic recording flux, are in near contact with the tape to effect writing sharp transitions, and so that the read element is in near contact with the tape to provide effective coupling of the magnetic field from the tape to the read element.

"Tape drives have conventionally used a servo system to keep the write/read heads in the correct lateral location on the tape. The difference between the correct location and actual location of the heads is referred to as position error signal (PES).

"Current servo systems implement a fixed threshold such that if the PES is larger than the threshold, the writing of the heads will be stopped to prevent overwriting of adjacent tracks. This threshold is referred to as the stopwrite (SW) threshold.

"However, it is difficult to pick the appropriate SW threshold due to the differences in distributions of PES data for different drives and/or different tapes. Another drawback is that when a particular predetermined SW threshold is used, the drive may write the data without any apparent error, when actually the adjacent tracks have been overwritten, rendering the data therein unreadable. This result is highly undesirable."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventor's summary information for this patent application: "A method according to one embodiment includes updating a first value based on a current position error signal sample, determining whether the first value exceeds a predetermined threshold, determining a stopwrite threshold based on the first value when the first value exceeds the predetermined threshold, determining whether the current position error signal sample exceeds the stopwrite threshold, disabling writing when the current position error signal sample exceeds the stopwrite threshold, and enabling writing when the current position error signal sample does not exceed the stopwrite threshold.

"A computer program product according to one embodiment includes a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a controller to cause the controller to perform the foregoing method.

"A data storage system according to one embodiment includes a head, a drive mechanism for passing a medium over the head, a controller electrically coupled to the magnetic head, and logic integrated with and/or executable by the controller, the logic being configured to perform the foregoing method.

"Any of these embodiments may be implemented in a magnetic data storage system such as a tape drive system, which may include a magnetic head, a drive mechanism for passing a magnetic medium (e.g., recording tape) over the magnetic head, and a controller electrically coupled to the magnetic head.

"Other aspects and embodiments of the present invention will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrate by way of example the principles of the invention.


"FIG. 1 is a schematic diagram of a simplified tape drive system according to one embodiment.

"FIG. 2 illustrates a side view of a flat-lapped, bi-directional, two-module magnetic tape head according to one embodiment.

"FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

"FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

"FIG. 2C is a detailed view of a partial tape bearing surface of a pair of modules.

"FIG. 3 is a partial tape bearing surface view of a magnetic head having a write-read-write configuration.

"FIG. 4 is a partial tape bearing surface view of a magnetic head having a read-write-read configuration.

"FIG. 5 depicts a method according to one embodiment.

"FIG. 6 is a flowchart of a method according to one embodiment.

"FIG. 7 is a top down view of a data track according to one embodiment.

"FIG. 8 is a graph according to one embodiment.

"FIG. 9 is a graph according to one embodiment."

For additional information on this patent application, see: Judd, Kevin B. Variable Stopwrite Threshold. Filed April 18, 2014 and posted August 21, 2014. Patent URL:

Keywords for this news article include: Information Technology, Information and Data Storage, International Business Machines Corporation.

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Source: Information Technology Newsweekly

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