METHOD FOR REDUCING WRITE AMPLIFICATION ON A DATA CARRIER WITH OVERLAPPING DATA TRACKS AND DEVICE THEREOF

• US 20150255114A1
• Filed: 03/02/2015
• Published: 09/10/2015
• Est. Priority Date: 03/04/2014
• Status: Active Grant

• Current Assignee: Inodyn Newmedia GmbH
• Original Assignee: Inodyn Newmedia GmbH
• Inventors: Pantel, Lothar
• Granted Patent: US 9,117,488 B1
• Time in Patent Office: Days
• 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 novel symmetrical band is disclosed, which may be used in connection with shingled magnetic recording (SMR) in order to reduce write amplification (read-modify-write). Depending on the embodiment, overlapping data tracks diverge from, or converge to the center of each symmetrical band. Associated guard regions may be located at the center, or at the band boundaries, and are shared such that the excess width of a write element is caught by the guard regions from both sides. A symmetrical band may reduce the maximum write amplification by more than half. A hard disk controller may maintain the number of taken or empty tracks on both sides of each symmetrical band substantially equal at every fill level.

Claims

1. A method for reducing write amplification on a data carrier surface with overlapping data tracks, comprising:

a) writing overlapping data tracks on said data carrier surface, establishing a plurality of symmetrical bands with overlaps in opposite radial directions essentially between the middle of each symmetrical band and the band boundaries, wherein associated guard regions are located essentially in the middle of each symmetrical band, or at the band boundaries, wherein the excess width of data tracks, written on both tracks adjacent to each guard region, is caught by said guard regions from both sides,

b) maintaining the number of taken or empty tracks on both sides of each symmetrical band substantially equal at every fill level of each symmetrical band.

2. The method of claim 1, further comprising symmetrical bands whose associated guard regions are located in the middle or near the middle of each symmetrical band, both tracks adjacent to each guard region being written such that the excess width of a write element is caught by said guard region from both sides.

3. The method of claim 2, wherein overlapping data tracks, written by said write element, converge from both outer boundaries of each symmetrical band inward, toward said guard regions, establishing overlaps in opposite radial directions within each symmetrical band.

4. The method of claim 2, further comprising:

a) writing data substantially to the two outermost tracks on both sides of each symmetrical band, essentially in a first filling stage,

b) writing data substantially to the next inwardly adjacent tracks on both sides of each symmetrical band, essentially in a second filling stage.

5. The method of claim 4, further comprising writing data substantially to the two innermost tracks adjacent to the guard region of each symmetrical band, essentially in a final filling stage.

6. The method of claim 1, further comprising at least two adjacent symmetrical bands whose shared guard region is located at the common boundary of said symmetrical bands, the tracks adjacent to said common boundary being written such that the excess width of a write element is caught by said shared guard region from both sides.

7. The method of claim 6, wherein overlapping data tracks, written by said write element, diverge from a location in the middle or near the middle of each symmetrical band outward, toward said shared guard regions, establishing overlaps in opposite radial directions within each symmetrical band.

8. The method of claim 6, further comprising:

a) writing data substantially to the two innermost tracks in the middle of each symmetrical band, essentially in a first filling stage,

b) writing data substantially to the next outwardly adjacent tracks on both sides of each symmetrical band, essentially in a second filling stage.

9. The method of claim 8, further comprising writing data substantially to the two outermost tracks on both sides of each symmetrical band, essentially in a final filling stage, said outermost tracks being adjacent to the shared guard regions.

10. The method of claim 1, further comprising:

a) writing data substantially to every second, third, or n-th track on both sides of each symmetrical band, essentially in a first filling stage, where n is a natural number greater than three,

b) writing data substantially to all remaining, empty tracks of each symmetrical band, essentially in at least one subsequent filling stage.

11. The method of claim 1, further comprising writing frequently changing data to tracks adjacent to said guard regions and/or writing archive data to tracks that have an increased distance to said guard regions within each symmetrical band.

12. The method of claim 1, wherein:

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

b) physical sectors on said tracks are assigned and/or remapped by means of a logical block address mapping technique.

13. A storage device optimized for low write amplification, comprising:

a) at least one data carrier surface,

b) at least one write element whose data track width exceeds the track width of a read element by an excess width,

c) a plurality of symmetrical bands each comprising overlapping data tracks, written by said write element on said data carrier surface with overlaps in opposite radial directions essentially between the middle of each symmetrical band and the band boundaries, wherein associated guard regions are located essentially in the middle of each symmetrical band, or at the band boundaries, wherein the excess width of data tracks, written on both tracks adjacent to each guard region, is caught by said guard regions from both sides,

d) a control unit configured to maintain the number of taken or empty tracks on both sides of each symmetrical band substantially equal at every fill level of each symmetrical band.

14. The storage device of claim 13, further comprising symmetrical bands whose associated guard regions are located in the middle or near the middle of each symmetrical band, both tracks adjacent to each guard region being written such that the excess width of said write element is caught by said guard region from both sides.

15. The storage device of claim 14, wherein overlapping data tracks, written by said write element, converge from both outer boundaries of each symmetrical band inward, toward said guard regions, establishing overlaps in opposite radial directions within each symmetrical band.

16. The storage device of claim 14, wherein said control unit is configured to:

a) add data substantially to the two outermost tracks on both sides of each symmetrical band, essentially in a first filling stage,

b) add data substantially to the next inwardly adjacent tracks on both sides of each symmetrical band, essentially in a second filling stage.

17. The storage device of claim 13, further comprising at least two adjacent symmetrical bands whose shared guard region is located at the common boundary of said symmetrical bands, the tracks adjacent to said common boundary being written such that the excess width of said write element is caught by said shared guard region from both sides.

18. The storage device of claim 17, wherein overlapping data tracks, written by said write element, diverge from a location in the middle or near the middle of each symmetrical band outward, toward said shared guard regions, establishing overlaps in opposite radial directions within each symmetrical band.

19. The storage device of claim 17, wherein said control unit is configured to:

a) add data substantially to the two innermost tracks in the middle of each symmetrical band, essentially in a first filling stage,

b) add data substantially to the next outwardly adjacent tracks on both sides of each symmetrical band, essentially in a second filling stage.

20. The storage device of claim 13, wherein:

a) said storage device is a hard disk drive that operates according to the shingled magnetic recording methodology,

b) said data carrier surface is a disk surface of said hard disk drive,

c) said control unit is a hard disk controller of said hard disk drive,

d) said control unit is configured to assign and/or remap physical sectors on said tracks by means of a logical block address mapping technique.