Tape drive emulation by removable disk drive and media formatted therefor

• US 6,389,503 B1
• Filed: 03/23/1998
• Issued: 05/14/2002
• Est. Priority Date: 08/04/1997
• Status: Expired due to Term

• Current Assignee: Tandberg Data Corporation
• Original Assignee: Exabyte Corporation (MidgardXXI, Inc.)
• Inventors: Freymuth, Lawrence A., Georgis, Steve
• Primary Examiner(s): Yoo, Do Hyun
• Assistant Examiner(s): Namazi, Mehdi
• Application Number:
  US09/045,691
• Time in Patent Office: 1,513 Days
• Field of Search: 395/500, 369/84, 369/59, 369/32, 711/118, 711/4, 360/15, 360/61, 714/6, 714/758
• US Class Current: 711/4
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0661 Format or protocol conversion arrangements
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0676 Magnetic disk device

Abstract

A disk drive detects whether a disk inserted therein has a frame-based enhanced formatting. Disks having the frame-based enhanced formatting are readable by enhanced drives, e.g., those with the tape drive emulators. The frame-based enhanced formatting imposes on the data (1) an data organization, imperceptible to disk drive 22, for rendering the data expressible and locatable in a tape drive format, and (2) an additional degree of error correction that provides enhanced data integrity necessary for data backup/restore operations. The detection stems from a secondary formatting operation of the invention in which a format type identification is recorded on the disk. Preferably, the format type identification is recorded as one disk sector at a beginning logical block address of the disk, and forms part of a volume header frame. The volume header frame is followed by a directory comprising one or more directory frames.

Claims

1. A data storage system which connects to a host computer for performing one of a data backup operation and data restore operation, the data storage system comprising:

a disk drive which transduces information in a sector format with respect to a rotating disk,

a tape drive emulator connected between the disk drive and the host computer, the tape drive emulator interfacing with the host computer using a set of commands applicable to a tape drive, the tape drive emulator communicating data to and from the disk drive whereby the data is transduced relative to the disk in the sector format,

wherein the tape drive emulator generates a set of data, the set of data being recorded in a predetermined plural number of sectors on the disk, the set of data having error correction bytes generated over the set, the error correction bytes being sufficient to recover a sector of the disk not readable by the disk drive.

2. The system of claim 1, wherein the predetermined plural number of sectors is forty.

3. The system of claim 1, wherein error correction information is stored on two of the predetermined plural number of sectors.

4. The system of claim 1, wherein the predetermined plural number of sectors is sixteen hundred.

5. The system of claim 1, wherein error correction information is stored on eighty of the predetermined plural number of sectors.

6. The system of claim 1, wherein user data included in a set corresponds to a buffer block of data generated by the tape drive.

7. The system of claim 1, wherein the tape drive emulator generates plural frames of data, each of the frames of data being recording on the predetermined plural number of sectors on the disk, each frame having the error correction bytes generated thereover, at least some of the frames serving as directory frames, the directory frames having stored therein references to storage locations on the disk of data delineators.

8. The system of claim 7, wherein the data delineators include one of logical block numbers, file marks, and set marks.

9. The system of claim 1, wherein the disk is a rotating magnetic disk.

10. The system of claim 1, wherein the disk is a removable disk.

11. A data storage system which connects to a host computer for performing one of a data backup operation and data restore operation, the data storage system comprising:

a disk drive which transduces information on a rotating disk,

a tape drive emulator connected between the disk drive and the host computer, the tape drive emulator comprising;

a compression engine which compresses logical blocks obtained from the host computer;

a packer unit which packs compressed logical blocks;

an error correction encoder which generates error correction bytes over the logical blocks; and

wherein the compressed logical blocks and error correction bytes are transmitted as a set to the disk drive, the set being recordable in a predetermined plural number of sectors on the disk drive.

12. The system of claim 11, wherein the tape drive emulator further comprises a header generator which generates header bytes for inclusion in a frame of the set, the header bytes including frame identifying information.

13. The system of claim 11, wherein the predetermined plural number of sectors is forty.

14. The system of claim 11, wherein error correction information is stored on two of the predetermined plural number of sectors.

15. The system of claim 11, wherein the predetermined plural number of sectors is sixteen hundred.

16. The system of claim 11, wherein error correction information is stored on eighty of the predetermined plural number of sectors.

17. The system of claim 11, wherein a set is a frame, and wherein user data included in a frame corresponds to a buffer block of data generated by the tape drive.

18. The system of claim 11, wherein the error correction bytes are sufficient to recover a sector of the disk not readable by the disk drive.

19. The system of claim 11, wherein the disk is a rotating magnetic disk.

20. The system of claim 11, wherein the disk is a removable disk.

21. The apparatus of claim 11, wherein the error correction bytes are sufficient to recover a sector of the disk not readable by the disk drive.

22. A method of storing computer data on a rotating magnetic disk, the method comprising:

using a tape drive emulator connected between a disk drive and a host computer to interface with the host computer using a set of commands applicable to a tape drive,

communicating data from the tape drive emulator to and from the disk drive whereby the data is transduced relative to the disk in a sector format,

generating with the tape drive emulator a set of data, the set of data being recorded in a predetermined plural number of sectors on the disk, the set of data having error correction bytes generated over the set, the error correction bytes being sufficient to recover a sector of the disk not readable by the disk drive.

23. The method of claim 22, wherein the set includes a frame, each frame having the error correction bytes generated thereover, and further comprising generating a frame header and including the frame header in the set, the frame header being covered by the error correction bytes.

24. The method of claim 23, further comprising generating a CRC bytes for the frame and including the CRC bytes in the frame, the error correction bytes covering the CRC bytes.

25. The method of claim 22, further comprising compressing the user data prior to forming the set.

26. The method of claim 22, wherein the predetermined plural number of sectors is forty.

27. The method of claim 22, wherein error correction information is stored on two of the predetermined plural number of sectors.

28. The method of claim 22, wherein the predetermined plural number of sectors is sixteen hundred.

29. The method of claim 22, wherein error correction information is stored on eighty of the predetermined plural number of sectors.

30. The method of claim 22, wherein user data included in a set corresponds to a buffer block of data generated by the tape drive.

31. The method of claim 22, further comprising the tape drive emulator generating plural frames of data, each of the frames of data being recording on the predetermined plural number of sectors on the disk, each frame having the error correction bytes generated thereover, at least some of the frames serving as directory frames, the directory frames having stored therein references to storage locations on the disk of data delineators.

32. The method of claim 31, wherein the data delineators include one of logical block numbers, file marks, and set marks.

33. The method of claim 22, wherein the disk is a rotating magnetic disk.

34. The method of claim 22, wherein the disk is a removable disk.

35. A method of storing computer data on a rotating magnetic disk, the method comprising:

using a tape drive emulator connected between a disk drive and a host computer to interface with the host computer using a set of commands applicable to a tape drive,

communicating data from the tape drive emulator to and from the disk drive whereby the data is transduced relative to the disk in a sector format,

recovering with the tape drive emulator a set of data, the set of data being recorded in a predetermined plural number of sectors on the disk, the set of data having error correction bytes generated over the set, the error correction bytes being sufficient to recover a sector of the disk not readable by the disk drive.

36. The method of claim 35, wherein the predetermined plural number of sectors is forty.

37. The method of claim 35, wherein error correction information is stored on two of the predetermined plural number of sectors.

38. The method of claim 35, wherein the predetermined plural number of sectors is sixteen hundred.

39. The method of claim 35, wherein error correction information is stored on eighty of the predetermined plural number of sectors.

40. The method of claim 35, further comprising the tape drive emulator generating plural frames of data, each of the frames of data being recording on the predetermined plural number of sectors on the disk, each frame having the error correction bytes generated thereover, at least some of the frames serving as directory frames, the directory frames having stored therein references to storage locations on the disk of data delineators.

41. The method of claim 40, wherein the data delineators include one of logical block numbers, file marks, and set marks.

42. The method of claim 35, wherein the disk is a rotating magnetic disk.

43. The method of claim 35, wherein the disk is a removable disk.

44. A rotating information storage media comprising:

a disk formatted with sectors, a set of data being recorded over a predetermined plural number of the sectors, the set of data having error correction bytes generated over the set of data, the error correction bytes being sufficient to recover a sector of the disk not readable by a disk drive.

45. The media of claim 44, wherein the predetermined plural number of sectors is forty.

46. The media of claim 44, wherein the error correction information is stored on two of the predetermined plural number of sectors.

47. The media of claim 44, wherein the predetermined plural number of sectors is sixteen hundred.

48. The media of claim 44, wherein the error correction information is stored on eighty of the predetermined plural number of sectors.

49. The media of claim 44, wherein the user data included in the set corresponds to a buffer block of data generated by the tape drive.

50. A tape drive emulator connected between a disk drive and a host computer which interfaces with said host computer using a set of commands applicable to a tape drive, the tape drive emulator generating a set of data for recordation in a predetermined plural number of sectors on a rotating information storage media, the set of data having error correction bytes generated over the set of data, the error correction bytes being sufficient to recover a sector of a disk not readable by the disk drive.

51. The tape drive emulator of claim 50, wherein the tape drive emulator generates plural frames of data, each of the frames of data being recorded on the predetermined plural number of sectors on the disk, each frame having the error correction bytes generated thereover, at least some of the frames serving as directory frames, the directory frames having stored therein references to storage locations on the disk of data delineators.

52. The tape drive emulator of claim 51, wherein the data delineators include one of logical block numbers, file marks, and set marks.

53. A method of formatting a rotating disk upon which information is recorded, the method comprising recording on the disk a format type identification, the format type identification being interpretable to indicate that the disk is compatible with transducing a multi-sectored set of data, the set of data being recordable or having been recorded in a predetermined plural number of sectors on the disk, the set of data having set error correction bytes generated over the set, the error correction bytes being sufficient to recover a sector of the disk not readable by a disk drive.

54. The method of claim 53, wherein the format type identification is recorded at a beginning logical block address of the disk.

55. The method of claim 53, further comprising recording on the disk the format type identification as part of a volume header frame.

56. The method of claim 55, further comprising recording a partition table as part of the volume header frame.

57. The method of claim 53, wherein the format type identification has a length of one disk sector.

58. The method of claim 53, further comprising recording on the disk at least one directory frame.

59. The method of claim 58, further comprising recording on the disk the at least one directory frame following recording of the format type identification.

60. The method of claim 59, wherein the predetermined location on the disk is the first logical block address of the disk.

61. The method of claim 59, wherein the predetermined unique pattern indicative of an enhanced format has a length of one disk sector.

62. A rotating information storage media having:

a first layer format whereby the media is formatted with sectors;

a format type identification type stored therein indicating that the media has a second layer format;

wherein according to the second layer format a multi-sectored set of data is recordable or has been recorded in a predetermined plural number of sectors on a disk, the set of data having error correction bytes generated over the set, the error correction bytes being sufficient to recover a sector of the disk not readable by the disk drive.

63. The media of claim 62, wherein the format type identification is recorded at a beginning logical block address of the media.

64. The media of claim 63, wherein the format type identification is recorded as part of a volume header frame.

65. The media of claim 64, wherein a partition table is recorded as part of the volume header frame.

66. The media of claim 63, wherein the format type identification has a length of one disk sector.

67. The media of claim 63, wherein the media also has at least one directory frame recorded thereon.

68. The media of claim 67, wherein the at least one directory frame follows recording of the format type identification.

69. A method of operating a disk drive, the method comprising:

reading a predetermined location on a disk to ascertain a format type identification of the disk;

comparing information obtained from the predetermined location with a predetermined unique pattern indicative of an enhanced format and, in accordance with the comparison; and

providing an indication whether the disk is compatible with transducing a multi-sectored set of data, the set of data being recordable or having been recorded in a predetermined plural number of sectors on the disk, the set of data having set error correction bytes generated over the set, the error correction bytes being sufficient to recover a sector of the disk not readable by the disk drive.