Retrieval of damaged payload data on a shingled magnetic recording data carrier

• US 9,336,096 B2
• Filed: 03/02/2015
• Issued: 05/10/2016
• Est. Priority Date: 03/04/2014
• Status: Active Grant

• Current Assignee: Inodyn Newmedia GmbH
• Original Assignee: Inodyn Newmedia GmbH
• Inventors: Pantel, Lothar
• Primary Examiner(s): Dinh, Tan X
• Application Number:
  US14/636,006
• Publication Number:
  US 20150254144A1
• Time in Patent Office: 435 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 12/10 Address translation
• CPC Class Codes: G06F 2212/1032 Reliability improvement, data loss prevention, degraded operation etc
• CPC Class Codes: G06F 2212/152 Virtualized environment, e.g. logically partitioned system
• CPC Class Codes: G06F 2212/21 Employing a record carrier using a specific recording technology
• CPC Class Codes: G06F 2212/657 Virtual address space management
• CPC Class Codes: G06F 2212/70 Details relating to dynamic memory management
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0673 Single storage device
• CPC Class Codes: G06F 3/0676 Magnetic disk device
• CPC Class Codes: G11B 20/1217 on discs
• CPC Class Codes: G11B 20/1252 for discontinuous data, e.g. digital information signals, computer programme data
• CPC Class Codes: G11B 2020/1238 track, i.e. the entire a spirally or concentrically arranged path on which the recording marks are located

Abstract

A defect management system for storage devices is disclosed, which may be used in connection with shingled magnetic recording (SMR). Overlapping data tracks, separated by guard regions, are written by a write element whose track width is at least twice as wide as the track width of a read element. Depending on the embodiment, data recovery of a defective track or sector is attained by evaluating the contents of an adjacent track or guard region: if the adjacent track or guard region encompasses equivalent data, due to the width of the write element, this data may be used as a complement or as a substitute for the defective track or sector. This may reduce the risk of data loss. The capacity of a storage device may be increased by balancing out the probability of read errors with the probability that an adjacent track may encompass equivalent data.

Claims

1. A method for the retrieval of payload data that are corrupted due to a defective section on a data carrier surface, comprising:

a) providing a first track and at least a subsequent second track that is adjacent to said first track, said first and second track being located in an area of said data carrier surface that is configured for shingled magnetic recording,

b) writing a data track on at least a section of said first and second track in a single pass by means of a write element whose data track width covers at least said first and second track, and maintaining management data including the information that at least said first and second track temporarily encompass equivalent data within said section,

c) reading, at a later stage, data from said section of said first track by means of a read element and evaluating by means of error control the accuracy of the data, and in the event that the data are inaccurate;

d) determining whether said management data still indicate that at least said first and second track encompass equivalent data within said section, and if this is the case;

e) reading data from at least said second track by means of said read element,

f) using at least a part of the data derived from at least said second track as a complement or as a substitute for the inaccurate data derived from said first track.

2. The method of claim 1, wherein said section of said first and second track extends to the entire first and second track.

3. The method of claim 1, wherein:

a) at least a subsequent third track is located adjacent to said second track,

b) a data track is written on at least a section of said first, second, and third track in a single pass by means of a write element whose data track width covers at least said first, second, and third track,

c) said management data include the information that at least said first, second, and third track temporarily encompass equivalent data within said section,

d) data derived from at least said second track, said third track, or a combination thereof are used as a complement or as a substitute for the inaccurate data derived from said first track.

4. The method of claim 1, wherein said first and second track are members of a plurality of tracks grouped into bands separated by tracks designated as guard regions, wherein, in the event that inaccurate data are read from said first track, it is checked whether at least said subsequent second track is designated as a guard region, and if this is the case, data from at least said guard region are read by means of said read element and are used at least in part as a complement or as a substitute for the inaccurate data derived from said first track.

5. The method of claim 1, further comprising increasing the capacity of said data carrier surface by balancing out the probability that defective sections do occur with the probability that tracks or guard regions adjacent to defective sections encompass, at least in part, equivalent data.

6. The method of claim 1, wherein said first and second track are members of a plurality of tracks grouped into at least one symmetrical band, wherein shingled data tracks, written by said write element, converge inward from both outer boundaries of said symmetrical band, toward a guard region located in the middle or near the middle of said symmetrical band, establishing overlaps in opposite radial directions within said symmetrical band, both tracks adjacent to said guard region being written such that the data track width of said write element is caught by said guard region from both sides.

7. The method of claim 6, further comprising:

a) displacing said guard region onto the physical location of a defective section located within said symmetrical band,

b) adjusting the order of shingled data tracks within said symmetrical band, taking into account the new physical location of said guard region,

c) storing data on at least the former physical location of said guard region.

8. The method of claim 1, wherein:

a) said section of said first track and said section of said second track each consists of one or more physical sectors,

b) said first and second track are members of a plurality of tracks on said data carrier surface,

c) said plurality of tracks are grouped into bands that are separated by tracks designated as guard regions,

d) said management data are processed by means of a hard disk controller,

e) said data carrier surface is a disk surface of a hard disk drive that operates according to the shingled magnetic recording methodology.

9. A method for the retrieval of payload data that are corrupted due to a defective section on a data carrier surface, comprising:

a) providing a first track and at least a subsequent second track that is adjacent to said first track, said first and second track being located in an area of said data carrier surface that is configured for shingled magnetic recording,

b) writing a data track on at least a section of said first and second track in a single pass by means of a write element whose data track width covers at least said first and second track,

c) reading, at a later stage, data from said section of said first track by means of a read element and evaluating by means of error control the accuracy of the data, and in the event that the data are inaccurate;

d) reading data from at least said second track by means of said read element,

e) comparing data derived from said first track with data derived from at least said second track by means of a decision criterion, and if the data are sufficiently equal;

f) using at least a part of the data derived from at least said second track as a complement or as a substitute for the inaccurate data derived from said first track.

10. The method of claim 9, wherein said decision criterion is a threshold value and involves to calculate the percentage of matching bits, bytes, raw signal, or a combination thereof at least within a section of said first and second track.

11. The method of claim 9, further comprising reading data from at least one track or guard region located in the vicinity of said first track and using at least a part of the data as a complement or as a substitute if the data are sufficiently equal to the inaccurate data derived from said first track.

12. The method of claim 9, further comprising increasing the capacity of said data carrier surface by balancing out the probability that defective sections do occur with the probability that tracks or guard regions adjacent to defective sections encompass, at least in part, equivalent data.

13. The method of claim 9, wherein said first and second track are members of a plurality of tracks grouped into at least one symmetrical band, wherein shingled data tracks, written by said write element, converge inward from both outer boundaries of said symmetrical band, toward a guard region located in the middle or near the middle of said symmetrical band, establishing overlaps in opposite radial directions within said symmetrical band, both tracks adjacent to said guard region being written such that the data track width of said write element is caught by said guard region from both sides.

14. The method of claim 13, further comprising:

a) displacing said guard region onto the physical location of a defective section located within said symmetrical band,

b) adjusting the order of shingled data tracks within said symmetrical band, taking into account the new physical location of said guard region,

c) storing data on at least the former physical location of said guard region.

15. The method of claim 9, wherein:

a) said section of said first track and said section of said second track each consists of one or more physical sectors,

b) said first and second track are members of a plurality of tracks on said data carrier surface,

c) said plurality of tracks are grouped into bands that are separated by tracks designated as guard regions,

d) comparing data derived from said first track with data derived from at least said second track is processed by means of a hard disk controller,

e) said data carrier surface is a disk surface of a hard disk drive that operates according to the shingled magnetic recording methodology.

16. A storage device capable of retrieving payload data that are corrupted due to a defective section on a data carrier surface, comprising:

a) a first track and at least a subsequent second track that is adjacent to said first track, said first and second track being located in an area of said data carrier surface that is configured for shingled magnetic recording,

b) a write element whose data track width covers at least said first and second track,

c) a data track on at least a section of said first and second track written in a single pass by means of said write element, and management data including the information that at least said first and second track temporarily encompass equivalent data within said section,

d) a read element, and

e) a control unit configured to;

i) read data from said section of said first track by means of said read element, wherein the accuracy of the data is evaluated by means of error control, and for the situation that the data are inaccurate, said control unit is configured to;

ii) determine whether said management data still indicate that at least said first and second track encompass equivalent data within said section, and for the situation that this proves true, said control unit is configured to;

iii) read data from at least said second track by means of said read element, wherein at least a part of the data is used as a complement or as a substitute for the inaccurate data derived from said first track.

17. The storage device of claim 16, wherein said first and second track are members of a plurality of tracks grouped into bands separated by tracks designated as guard regions, wherein, for the situation that inaccurate data are read from said first track, said control unit further is configured to check whether at least said subsequent second track is designated as a guard region, and for the situation that this proves true said control unit further is configured to read data from at least said guard region by means of said read element, wherein at least a part of the data is used as a complement or as a substitute for the inaccurate data derived from said first track.

18. The storage device of claim 16, wherein said data carrier surface has an increased capacity by exploiting error tolerances such that an increased probability that defective sections do occur is balanced out with the probability that tracks or guard regions adjacent to defective sections encompass, at least in part, equivalent data.

19. The storage device of claim 16, wherein:

a) said section of said first track and said section of said second track each consists of one or more physical sectors,

b) said first and second track are members of a plurality of tracks on said data carrier surface,

c) said plurality of tracks are grouped into bands that are separated by tracks designated as guard regions,

d) said control unit is a hard disk controller,

e) said management data are processed by means of said hard disk controller,

f) said data carrier surface is a disk surface of a hard disk drive that operates according to the shingled magnetic recording methodology.

20. A storage device capable of retrieving payload data that are corrupted due to a defective section on a data carrier surface, comprising:

a) a first track and at least a subsequent second track that is adjacent to said first track, said first and second track being located in an area of said data carrier surface that is configured for shingled magnetic recording,

b) a write element whose data track width covers at least said first and second track,

c) a data track on at least a section of said first and second track written in a single pass by means of said write element,

d) a read element, and

e) a control unit configured to;

i) read data from said section of said first track by means of said read element, wherein the accuracy of the data is evaluated by means of error control, and for the situation that the data are inaccurate, said control unit is configured to;

ii) read data from at least said second track by means of said read element, wherein data derived from said first track is compared with data derived from at least said second track by means of a decision criterion, and for the situation that the data are sufficiently equal, said control unit is configured to;

iii) use at least a part of the data derived from at least said second track as a complement or as a substitute for the inaccurate data derived from said first track.

21. The storage device of claim 20, wherein said decision criterion is a threshold value and involves to calculate the percentage of matching bits, bytes, raw signal, or a combination thereof at least within a section of said first and second track.

22. The storage device of claim 20, wherein said data carrier surface has an increased capacity by exploiting error tolerances such that an increased probability that defective sections do occur is balanced out with the probability that tracks or guard regions adjacent to defective sections encompass, at least in part, equivalent data.

23. The storage device of claim 20, wherein:

a) said section of said first track and said section of said second track each consists of one or more physical sectors,

b) said first and second track are members of a plurality of tracks on said data carrier surface,

c) said plurality of tracks are grouped into bands that are separated by tracks designated as guard regions,

d) said control unit is a hard disk controller,

e) said data carrier surface is a disk surface of a hard disk drive that operates according to the shingled magnetic recording methodology.