Efficient multichannel data format using variable-length headers

Patent metadata

Field	Value
Publication number	US-9601160-B2
Application number	US-201615078975-A
Country	US
Kind code	B2
Filing date	Mar 23, 2016
Priority date	Mar 31, 2015
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

In one embodiment, a computer-implemented method includes writing a data set to a first write section of a magnetic medium and rewriting at least some of the data set as rewritten CWI- 4 sets to a rewrite section of the magnetic medium. The data set includes a plurality of sub data sets, each sub data set including a data array organized in rows and columns. Each row of the data array includes four interleaved C1 codewords (a CWI- 4 ). A first portion of the data set is stored as CWI- 4 sets to the first write section of the magnetic medium with first headers. Each rewritten CWI- 4 set is stored to the rewrite section of the magnetic medium as a number of rewritten CWI- 4 s having corresponding rewrite headers. Also, a length of any one of the rewrite headers is greater than a length of any one of the first headers.

First claim

What is claimed is:

1. A computer-implemented method, comprising:
writing a data set to a first write section of a magnetic medium, the data set comprising a plurality of sub data sets, each sub data set comprising a data array organized in rows and columns, each row of the data array comprising four interleaved C 1 codewords (a CWI- 4 ), wherein a first portion of the data set is stored as CWI- 4 sets to the first write section of the magnetic medium with first headers, a CWI- 4 set comprising a fixed number of M concurrently written CWI- 4 s having M corresponding first headers; and
rewriting at least some of the data set as rewritten CWI- 4 sets to a rewrite section of the magnetic medium, wherein each rewritten CWI- 4 set is stored to the rewrite section of the magnetic medium as M rewritten CWI- 4 s having M corresponding rewrite headers,
wherein the rewritten CWI- 4 sets are determined based on errors being detected in CWI- 4 s stored in the first write section of the magnetic medium, and
wherein a length of any one of the rewrite headers is greater than a length of any one of the first headers.

2. The method as recited in claim 1 , wherein the data set comprises P CWI- 4 sets, wherein P is at least one of: modulo 8 , and an integer multiple of M.

3. The method as recited in claim 1 , further comprising detecting the errors in the CWI- 4 s stored in the first write section of the magnetic medium using a read-while-write process.

4. The method as recited in claim 1 , wherein each of the first headers is 4 bytes in length, and wherein all CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s with corresponding first headers.

5. The method as recited in claim 1 , further comprising writing a remaining portion of the data set not including the first portion of the data set to the first write section of the magnetic medium as CWI- 4 sets without headers.

6. The method as recited in claim 5 , wherein each of the first headers is 4 bytes in length, wherein odd numbered CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s without headers, wherein even numbered CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s with corresponding first headers, and wherein the CWI- 4 sets stored as CWI- 4 s without headers are interleaved with the CWI- 4 sets stored as CWI- 4 s with the corresponding first headers.

7. The method as recited in claim 5 , wherein each of the first headers is 8 bytes in length, wherein odd numbered CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s without headers, wherein even numbered CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s with corresponding first headers, and wherein the CWI- 4 sets stored as CWI- 4 s without headers are interleaved with the CWI- 4 sets stored as CWI- 4 s with the corresponding first headers.

8. The method as recited in claim 5 , wherein each of the first headers is 8 bytes in length, wherein a data set comprises 384 CWI- 4 sets, wherein 380 CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s without headers, and wherein 4 CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s with corresponding first headers.

9. The method as recited in claim 1 , wherein each of the rewrite headers is 12 bytes in length, and wherein the magnetic medium is a magnetic tape housed in a tape cartridge operable in a tape drive.

10. A computer-implemented method, comprising:
writing a data set to a first write section of a magnetic medium, the data set comprising a plurality of sub data sets, each sub data set comprising a data array organized in rows and columns, each row of the data array comprising four interleaved C 1 codewords (a CWI- 4 ), wherein a first portion of the data set is stored as CWI- 4 sets to the first write section of the magnetic medium with first headers, a CWI- 4 set comprising a fixed number of M concurrently written CWI- 4 s having M corresponding first headers; and
rewriting at least some of the data set as rewritten CWI- 4 sets to a rewrite section of the magnetic medium, wherein each rewritten CWI- 4 set is stored to the rewrite section of the magnetic medium as M rewritten CWI- 4 s having M corresponding rewrite headers,
wherein the rewritten CWI- 4 sets are determined based on errors being detected in CWI- 4 s stored in the first write section of the magnetic medium,
wherein the data set comprises P CWI- 4 sets, wherein P is at least one of: modulo 8 , and an integer multiple of M, and
wherein a length of any one of the rewrite headers is greater than a length of any one of the first headers.

11. The method as recited in claim 10 , further comprising detecting the errors in the CWI- 4 s stored in the first write section of the magnetic medium using a read-while-write process.

12. The method as recited in claim 10 , wherein each of the first headers is 4 bytes in length, and wherein all CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s with corresponding first headers.

13. The method as recited in claim 10 , further comprising writing a remaining portion of the data set not including the first portion of the data set to the first write section of the magnetic medium as CWI- 4 sets without headers.

14. The method as recited in claim 13 , wherein each of the first headers is 4 bytes in length, wherein odd numbered CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s without headers, wherein even numbered CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s with corresponding first headers, and wherein the CWI- 4 sets stored as CWI- 4 s without headers are interleaved with the CWI- 4 sets stored as CWI- 4 s with the corresponding first headers.

15. The method as recited in claim 13 , wherein each of the first headers is 8 bytes in length, wherein odd numbered CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s without headers, wherein even numbered CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s with corresponding first headers, and wherein the CWI- 4 sets stored as CWI- 4 s without headers are interleaved with the CWI- 4 sets stored as CWI- 4 s with the corresponding first headers.

16. The method as recited in claim 13 , wherein each of the first headers is 8 bytes in length, wherein P equals 384, wherein 380 CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s without headers, and wherein 4 CWI- 4 sets are stored to the first write section of the magnetic medium as CWI- 4 s with corresponding first headers.

17. The method as recited in claim 10 , wherein each of the rewrite headers is 12 bytes in length, and wherein the magnetic medium is a magnetic tape housed in a tape cartridge operable in a tape drive.

18. A computer-implemented method, comprising:
writing a data set to a first write section of a magnetic medium, the data set comprising a plurality of sub data sets, each sub data set comprising a data array organized in rows and columns, each row of the data array comprising four interleaved C 1 codewords (a CWI- 4 ), wherein a first portion of the data set is stored as CWI- 4 sets to the first write section of the magnetic medium with first headers, a CWI- 4 set comprising a fixed number of M concurrently written CWI- 4 s having M corresponding first

Assignees

• IBM

Inventors

• Bentley Steven R
• Cideciyan Roy D
• Furrer Simeon
• Ohtani Kenji

Classifications

• G11B20/1201 Primary

  on tapes · CPC title

• G11B27/36 Primary

  Monitoring, i.e. supervising the progress of recording or reproducing {(for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06)} · CPC title

• G11B2020/183

  wherein at least one additional attempt is made to read or write the data when a first attempt is unsuccessful · CPC title

• G11B20/18

  Error detection or correction; Testing {, e.g. of drop-outs} · CPC title

• G11B5/09

  Digital recording · CPC title