Method for replacing defective sections on a data carrier with overlapping data tracks and device thereof

Abstract

A defect management for storage devices is disclosed, which may be used in connection with shingled magnetic recording (SMR). SMR uses bands, consisting of tracks, separated by guard regions. The replacement of a defective sector may be attained by placing a guard region onto the physical location of the defective sector. Depending on the embodiment, the boundaries of the bands and corresponding guard regions may be shifted. The portion of the disk surface which is necessary for the guard regions may simultaneously function as a spare sector area for defective sectors without additional space requirements. In at least one embodiment, an additional guard region reduces the write amplification, and in other embodiments, guard regions are placed onto tracks with an elevated number of primary defects.

What is claimed is: 
     
         1 . A method for replacing a defective section on a data carrier surface of a storage device configured for overlapping data tracks, comprising placing at least one guard region at least partly onto the physical location of said defective section. 
     
     
         2 . The method of  claim 1 , wherein said guard region completely covers said defective section. 
     
     
         3 . The method of  claim 1 , wherein said guard region comprises one single track, multiple adjacent tracks, a single track segment, or multiple track segments on adjacent tracks. 
     
     
         4 . The method of  claim 1 , further comprising:
 a) displacing at least one existing guard region onto the physical location of said defective section,   b) storing data on the former physical location of said guard region.   
     
     
         5 . The method of  claim 4 , wherein at least a part of the retrievable data from the track affected by said defective section is stored on the former physical location of said guard region. 
     
     
         6 . The method of  claim 4 , wherein at least that existing guard region is displaced onto the physical location of said defective section, which is closest to said defective section. 
     
     
         7 . The method of  claim 4 , further comprising shifting the boundaries of adjacent bands, so that the corresponding guard region gets positioned on said defective section. 
     
     
         8 . The method of  claim 7 , wherein the width of said adjacent bands is increased or decreased by the number of tracks, by which said guard region is displaced. 
     
     
         9 . The method of  claim 4 , further comprising displacing stored data, which is located on tracks in the semi-open interval, starting from the former physical location of said guard region up to and including the new physical location of said guard region, by a number of tracks derived from the width of said guard region, preserving the sequential order of said stored data throughout. 
     
     
         10 . The method of  claim 4 , wherein in the case that two or more defective sections are located in a band on different tracks, which are too far apart from one another to be covered by the width of a single guard region, both the upper and the lower boundaries of said band are shifted, the corresponding upper guard region and the corresponding lower guard region being respectively placed onto the physical locations of said defective sections. 
     
     
         11 . The method of  claim 4 , wherein in the case that two or more defective sections are located in a band on adjacent tracks, whose combined width is too large to be covered by a single guard region, both the upper and the lower boundaries of said band are pulled together entirely, the corresponding upper guard region and the corresponding lower guard region being placed next to each other on said adjacent tracks affected by said defective sections. 
     
     
         12 . The method of  claim 4 , further comprising equalizing the track count of a band by shifting the boundaries of adjacent bands to such an extent that the difference in the track count of said band is reduced. 
     
     
         13 . The method of  claim 1 , further comprising:
 a) placing at least one additional guard region onto the physical location of said defective section,   b) storing existing or future data, originally assigned to said defective section, in a reserve area instead.   
     
     
         14 . The method of  claim 1 , further comprising:
 a) scanning or testing the quality of at least one data carrier surface,   b) determining the quality of each track,   c) placing, by means of an optimization algorithm, guard regions preferentially onto tracks of poor or marginal quality.   
     
     
         15 . The method of  claim 1 , further comprising:
 a) detecting defective sections on the tracks of at least one data carrier surface,   b) counting the number of defective sections per track,   c) placing, by means of an optimization algorithm, guard regions preferentially onto tracks which contain an elevated number of defective sections.   
     
     
         16 . The method of  claim 1 , wherein
 a) said storage device is a hard disk drive which operates according to the shingled magnetic recording methodology,   b) said data carrier surface is a disk surface of said hard disk drive,   c) said overlapping data tracks are grouped into bands and are separated by guard regions in accordance with the shingled magnetic recording methodology,   d) said defective section is a defective sector.   
     
     
         17 . A data carrier surface having an optimized storage capacity, comprising:
 a) a plurality of overlapping data tracks, grouped into bands,   b) at least one defective section,   c) at least one guard region placed at least partly onto the physical location of said defective section.   
     
     
         18 . The data carrier surface of  claim 17 , wherein said guard region completely covers said defective section. 
     
     
         19 . The data carrier surface of  claim 17 , wherein said guard region comprises one single track, multiple adjacent tracks, a single track segment, or multiple track segments on adjacent tracks. 
     
     
         20 . The data carrier surface of  claim 17 , further comprising:
 a) a number of defective sections arbitrarily distributed across the plurality of tracks,   b) a plurality of guard regions positioned as often as possible on tracks of poor or marginal quality.   
     
     
         21 . The data carrier surface of  claim 20 , wherein the positions of said guard regions are optimized by means of an optimization algorithm, taking into account:
 a) a minimum and/or a maximum permissible number of tracks per band and/or   b) the quality level of each track and/or track sections and/or   c) the quality level of adjacent tracks and/or adjacent track sections and/or   d) the size, the width, or the severity level of a defective section.   
     
     
         22 . The data carrier surface of  claim 17 , further comprising:
 a) a number of defective sections arbitrarily distributed across the plurality of tracks, each track containing several defective sections, a single defective section, or no defective sections,   b) a plurality of guard regions positioned as often as possible on tracks with an elevated number of defective sections.   
     
     
         23 . The data carrier surface of  claim 17 , wherein the width of each guard region is adjusted individually depending on the size, the width, or the severity level of the defective section covered by said guard region and/or depending on the quality level of adjacent tracks or track sections, subsequent tracks being shifted corresponding to the adjusted width of said guard region. 
     
     
         24 . The data carrier surface of  claim 17 , wherein
 a) said data carrier surface is a disk surface of a hard disk drive which operates according to the shingled magnetic recording methodology,   b) said overlapping data tracks are recorded according to the shingled magnetic recording methodology,   c) said defective section is a defective sector.   
     
     
         25 . A storage device configured for overlapping data tracks, comprising:
 a) at least one data carrier surface,   b) a plurality of tracks on each data carrier surface grouped into bands and separated by guard regions,   c) an optimized number of tracks for each band, individually for each data carrier surface, such that the guard regions are positioned, as often as possible, on tracks of poor or marginal quality.