HDD sector format with reduced vulnerability to defects and burst errors
View Patent ↗Modified HDD sector formats have multiple sets of preamble data. The preambles are well separated so that any defect long enough to wipe out both preambles would also overwhelm the ECC.
1. A method for data storage, comprising:
rendering, from a data sector, at least two segments each including a respective sync preamble, such that a distance in data units between the sync preambles is no greater than a burst erasure correction capability of an error correction code (ECC), wherein the burst erasure correction capability is represented by a number of redundant parity symbols “T” associated with the ECC plus one and the distance is never more than 2T+1.
2. The method of claim 1 , wherein two and only two segments are established, the segments having different sizes from each other.
3. The method of claim 1 , wherein a multiple “n” of two segments are established, each with its own respective sync preamble, wherein “n” is an integer greater than one.
4. The method of claim 3 , wherein at least four segments per sector are established.
5. The method of claim 3 , wherein at least six segments per sector are established.
6. The method of claim 4 , wherein the segments have equal sizes.
7. The method of claim 1 , comprising interleaving segments of different data sectors.
8. The method of claim 1 , comprising establishing segment sizes at least in part based on radial location of the segments on a disk.
9. A hard disk drive, comprising: logic rendering plural sync preambles in at least one sector having a size of 512 bytes or 4 kB, the spacing between sync preambles being keyed to a burst erasure correction capability of an ECC executed by the HDD to recover from errors, wherein the sync preambles contain parity symbols and the burst erasure correction capability is represented by a number of redundant parity symbols “T” associated with the ECC plus one, the spacing never being more than 2T+1.
10. The HDD of claim 9 , wherein two and only two segments are established, the segments having different sizes from each other.
11. The HDD of claim 9 , wherein a multiple “n” of two segments are established, each with its own respective sync preamble, wherein “n” is an integer greater than one.
12. The HDD of claim 11 , wherein at least four segments are established.
13. The HDD of claim 12 , wherein the segments have equal sizes.
14. The HDD of claim 9 , wherein the logic interleaves segments of different data sectors.
15. The HDD of claim 9 , wherein the logic establishes segment sizes to ensure that no partial segment is established regardless of radial location of the segments on a disk.
16. A data storage system, comprising:
at least one data storage disk defining plural sectors; and
means for rendering at least one sector into at least two segments, each segment having a respective preamble containing sync data, the locations of the preambles relative to each other being based at least in part on the burst erasure correction capability of the ECC such that the preambles are never separated from each other by more than 2T+1 symbols, wherein T is a number of redundant parity symbols associated with the ECC.
17. The system of claim 16 , wherein the sector has a size of 4kB.
18. The system of claim 17 , comprising means for interleaving segments of different data sectors.
19. The system of claim 17 , comprising means for establishing sector sizes differently based on radial location of the segments on a disk.
20. The system of claim 16 , wherein two and only two segments are established, the segments having different sizes from each other.
21. The system of claim 16 , wherein a multiple “n” of two segments are established, each with its own respective sync preamble, wherein “n” is an integer greater than one.