Virtual addressing of optical storage media as magnetic tape equivalents

Filing Information

• Patent Number: US5455926
• Application Number: US8265514
• Filing date: 06/20/1994
• Issue date: 10/03/1995
• Predicted expiration date: 04/05/2008

• U.S. Classifications: 395/404  · 395/439  ·
• International Classifications: G06F 1200 ·
• International Classifications: 364DIG. 1;DIG. 2 ·
• Related U.S. Application Data:
  This is a continuation of application Ser. No. 07/633,265 filed Dec. 19, 1990, now abandoned, which application is itself a continuation of application Ser. No. 07/177,761 filed Apr. 5, 1988, now abandoned.
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Abstract

An optical disk storage system emulates a magnetic tape subsystem by virtual addressing of data recorded on write once optical disk media having a predetermined group of available sectors for rewriting a disk ID, a predetermined plurality of bands of available sectors for rewriting a virtual tape directory to virtual tape VSNs, and, available sectors for rewriting virtual tape maps and rewriting user records, the tape maps have data portions for simulating tape marks and interblock gap and for addressing blocks of data within the virtual tapes, the virtual tape directory has pointers for pointing to tape maps, and the system rewrites the tape directory, tape maps and user records so as to function as a rewritable magnetic tape.

Independent Claims | See all claims (41)

1. 1. A system for recording a plurality of virtual magnetic tapes, each of which includes user records, on optical disk, said optical disk recording system comprising:a record recording means for recording said user records of each of said plurality of virtual magnetic tapes on said optical disk, and for, at a later time, supplementally recording still further user records as represent any additions or alterations to any one or ones of the plurality of virtual magnetic tapes,a tape map recording means for recording on said optical disk a tape map respective of each one of the plurality of virtual magnetic tapes, each tape map including pointer data pointing to a location on said optical disk of the user records of an associated one of said plurality of virtual magnetic tapes, and each tape map being recorded on the optical disk separately from an associated one of said plurality of virtual magnetic tapes, and for, at a later time, supplementally recording a new tape map or maps respective of any one or ones of said plurality of virtual magnetic tapes as are, commensurate with the ability of the recording means to record further user records, updated, andmeans for recording upon the disc which individual one of possibly several historically sequential occurrences of each of the plurality of tape maps as correspond to each of the plurality of virtual magnetic tapes is newest, which newest tape maps will, in accordance with being supplementally recorded in accordance with all most recent revisions to the user records of a virtual magnetic tape, include pointer data to all most current revision user records of each virtual magnetic tape,wherein the user records of each and any of the plurality of virtual magnetic tapes are accessed during reading by reference to the pointer data of a newest associated tape map,wherein when a read reference proceeds through a newest tape map that is supplanting of, different than, and revised from a former tape map than such read reference is permissively to new user records that are supplanting of, and permissively different than and revised from, such User records as were accessed by the former tape map,wherein the virtual magnetic tapes are susceptible of being any of added, deleted or altered in whole or in part by (i) the supplemental recording by the record recording means of such further added or revised user records as prove pertinent, plus (ii) the supplemental recording by the tape map recording means of a new tape map that is referenceable during reading to access said added, deleted or altered virtual magnetic tape.
2. 4. A system for recording on an optical disk in an optical disk drive a plurality of magnetic tapes each having user records as a corresponding plurality of virtual magnetic tapes, said optical disk recording system comprising:a record recording means for recording said user records of each of said plurality of virtual magnetic tapes,a tape map recording means for recording on said optical disk tape maps respective of each one of the plurality of virtual magnetic tapes, each tape map including pointer data pointing to a location on said optical disk of the user records of an associated one of said plurality of virtual magnetic tapes, and each tape map being recorded separately from an associated one of said plurality of virtual magnetic tapes, anda tape directory recording means for recording tape directory data., the tape directory data including tape map pointer data pointing to a tape map of a respective one of the plurality of virtual magnetic tapes, andvirtual tape directory identification data recording means for recording data identifying each respective one of the plurality of virtual magnetic tapes, said virtual tape directory data being recorded separate from any of said user records.
3. 13. An optical disk recording system for recording, on an optical disk where data is recorded in sectors and that is insertable in an optical disk drive, a plurality of magnetic tapes each of which has user records as a corresponding plurality of virtual magnetic tapes, said optical disk recording system comprising:a record recording means for recording user records of said plurality of magnetic tapes as a corresponding plurality of virtual magnetic tapes,a tape map recording means for recording a plurality of tape maps corresponding to said plurality of virtual magnetic tapes, each of said plurality of tape maps being recorded on said optical disk separate from, but pointing to, said user records of a respective one of said plurality of virtual magnetic tapes, anda tape directory recording means for recording a plurality of tape directories each having a plurality of sectors, etch tape directory containing both an outdated tape directory and also an updated tape directory data having at least pointer data and identification data pointing to an associated one of said plurality of tape maps and identifying an associated one of said plurality of virtual magnetic tapes, said outdated tape directory data being recorded in a first sector of said tape directory so as to firstly identify an associated one of said plurality of virtual magnetic tapes, said updated tape directory data recorded in a current sector of said tape directory to currently identify an associated one of said plurality of virtual magnetic tapes.
4. 16. The optical disk recording system of claimwherein said tape directory recording means is recording a plurality of directories of which directories has a predetermined plurality of sectors for recording said outdated and updated tape directory data, a first directory of said plurality of directories being recorded at a predetermined location, said first directory having a last sector serving to record pointer data pointing to a next directory, and also having a last sector serving to record pointer data pointing to a successive next directory, a of said plurality of directories, and a current directory of said plurality of directories having a current sector serving to record said updated tape directory data, said updated tape directory data forebearing to be recorded in a last predetermined number of sectors of each of said plurality of directories until and unless a sector between said first sector and said last one of a predetermined number of sectors is defective.
5. 18. A method for identifying a selected one of a plurality of virtual magnetic tapes recorded on an optical disk that is recording data in sectors and that is insertable in an optical disk drive in a system that includes at least a computer with a memory, said optical disk having directories of virtual magnetic tapes recorded in one or more sectors of a plurality of directories each of which directories spans a plurality sectors, said directories of virtual magnetic tapes identifying all said plurality of virtual magnetic tapes, said method comprising the steps offirst searching the optical disk by reading in sequence said directories and then the sectors of each successive directory until a lowest unrecorded sector in a lowest directory is detected, thencausing said reading to back up one sector from the lowest detected unrecorded sector, thenreading the directory of virtual magnetic tapes recorded in this next-to-lowest sector into said memory, and thensecond searching the directory of virtual magnetic tapes in said memory to currently identify a selected one virtual magnetic tape.
6. 22. A method of writing a plurality of virtual magnetic tapes on an optical disk in an optical disk drive in and by a system that receives magnetic tape data including user records, said system having at least a computer and memory for writing the plurality of virtual magnetic tapes, said method comprising the steps oforganizing said user records of said magnetic tape data into a plurality of virtual magnetic tape user records,writing said plurality of virtual magnetic tape user records on said optical disk,generating a corresponding plurality of tape maps for said plurality of virtual magnetic tapes, said plurality of tape maps having pointers respectively pointing to each said plurality of virtual magnetic tape user records, andwriting said plurality of tape maps on said optical disk separate from and after, the writing of said plurality of virtual magnetic tape user records.
7. 27. A method for reading a plurality of magnetic tapes recorded on a single optical disk in an optical disk drive by, and by use of, a pre-existing computer system for reading magnetic tape data from magnetic tapes having user records, the user records that are read from the optical disk being recorded on said optical disk as a plurality of virtual magnetic tapes each of which has virtual magnetic tape user records, said optical disk recording tape map data for said plurality of virtual magnetic tapes, said tape map data including pointers respectively pointing to said virtual magnetic tape user records of said plurality of virtual magnetic tapes, said tape map data being recorded on said optical disk separate from said virtual magnetic tape user records, said method comprising the steps ofreading into said memory said tape map data,selecting from tape map data at least one of said record pointers serving to point to at least one of said virtual magnetic tape user records, andreading into said memory said at least one virtual magnetic tape user record.
8. 30. A method of maintaining a plurality of virtual magnetic tapes on a plurality of optical disks recorded in optical disk drives in a system that serves to emulate a magnetic tape subsystem that controls magnetic tape drives to read or writing magnetic tape user records and that is connected through a channel to a host computer transmitting channel commands within channel data formats, said system including a computer with memory for communicating through said channel commands within channel data formats, said magnetic tape user records being recorded on optical disks as the plurality of virtual magnetic tapes, each of said optical disks recording a plurality of tape maps each respectively for a corresponding one virtual magnetic tape, each tape map serving to point to respective virtual magnetic tape user records that are recorded separate from the tape map, said method comprising the steps ofreceiving one or more channel commands through said channel directing the accessing of magnetic tape user records on a one of the plurality of magnetic tapes, andreading said plurality of tape maps in order so as to determine a respective one of said plurality of virtual magnetic tapes in which is recorded said magnetic tape user records.
9. 37. A method, performed on an optical disc that may be written but once in each area thereof,of recording a plurality of virtual magnetic tapes each of which virtual magnetic tapes includes user records, andof re-recording revised ones of the virtual magnetic tapes particularly as are so revised by incorporation of new and updated user records,so that each of the user records of each of the virtual magnetic tapes may be addressably accessed in its most currently revised form as if it were a record upon a magnetic tape, the method of recording and re-recording virtual magnetic tapes on an optical disc comprising:first recording on the optical disc, all in a first area and each at an addressable location,the user records of each of the virtual magnetic tapes, and, at later times,still further user records as represent any additions or alterations to any one or ones of the virtual magnetic tapes; and, at the conclusion of each recording of the user records of one or more virtual magnetic tapes,second recording on the optical disc, at an addressable location of a second area thereof that is separate from the first area, tape maps, each of which tape maps is individually uniquely associated with a corresponding one of the virtual magnetic tapes, each of which tape maps includes pointer data pointing to the addressable locations on said optical disc of all the most current user records of an associated one of the virtual magnetic tapes; and also at the conclusion of each recording of the user records,third recording upon the disc, at a dedicated area thereof that is separate from the first area, a tape directory, which tape directory contains pointers to the addresses of the newest and most current tape map for each and every virtual magnetic tape, which newest tape map for each and any particular virtual magnetic tape will contain pointer data pointing to the addressable locations on the optical disc of all the most current revisions of all the user records of that particular virtual magnetic tape;wherein each and any particular sought-after one of the user records on each and any particular sought-after one of the virtual magnetic tapes may be addressably accessed in its most currently revised form just as if it were a record upon a magnetic tape by reading tape directories to find a most current one such tape directory, and then, by reading a pointer for to the tape map of a particular sought-after virtual magnetic tape that is contained in this newest tape directory, reading the most current tape map for this particular sought-after virtual magnetic tape, and then, by reference to the pointers to the newest user records that are contained in this newest tape map, reading the particular sought-after one of the user records.
10. 38. A method of addressably recording and re-recording on an optical disc a multiplicity of user records that are contained in plurality of virtual magnetic tapes, the optical disc recording and re-recording method comprising:recording and re-recording at first times any of the user records, and any selectively updated ones of the user records, of each of the plurality of virtual magnetic tapes, this recording and re-recording serving to record all the user records and all the selectively updated user records each in its own particular addressable location in a first area on the optical disc; and then, at a time subsequent to the each of recording or re-recording of the records at the first times,recording and re-recording at second times after the first times, tape maps, and successor tape maps, each in a second area, separate from the first area, on the optical disk, each tape map being associated with a corresponding one virtual magnetic tape, each tape map including pointer data pointing to addresses on the optical disc of each most-recently recorded one of all the user records of the associated one virtual magnetic tapes;wherein each successor, newer, tape map as is associated with a one virtual magnetic tape supersedes and renders obsolete when written the immediately earlier and older tape map as was previously associated with the same one virtual magnetic tape;wherein each successor, newer, tape map, includes, by virtue of being generated at a second time subsequent to the occasion of a previous recording or re-recording of user records at a first time, pointer data pointing to at least one most newly recorded user record of a virtual magnetic tape, but may also contain pointer data pointing to user records of the same virtual magnetic tape that were not immediately just recorded or rerecorded in the immediately preceding first time;wherein a recording surface of the disc is conserved because, although only changed and selectively updated user records are rewritten, all the most current user records of any particular one virtual magnetic tape may be addressably accessed through a single newest tape map associated with that particular one virtual magnetic tape.
11. 39. A method of recording on an optical disc a plurality of magnetic tapes each having user records, the optical disc recording method comprising:first recording in a first area of the optical disc the user records of each of the plurality of virtual magnetic tapes; thensecond recording in a second area, separate from he first area, of the optical disc tape maps respective of each one of the plurality of virtual magnetic tapes, each tape map including pointer data serving to point to a location on said optical disc of the user records of an associated one of said plurality of virtual magnetic tapes; and thenthird recording, in an area of the optical disc separate from the first area, tape directory data, the tape directory data including tape map pointer data serving to point to a tape map of a respective one of the plurality of virtual magnetic tapes.
12. 41.41. A method of recording on an optical disc a plurality of magnetic tapes, each of which magnetic tapes includes user records, as a plurality of virtual magnetic tapes, said method of recording the user records of magnetic tapes as virtual magnetic tapes on optical disc comprising:first recording user records of a plurality of magnetic tapes on the optical disc at a first area thereof as addressable records corresponding to a plurality of virtual magnetic tapes;second recording, in a second area of the optical disc separate from the first area, a plurality of tape maps corresponding to the plurality of virtual magnetic tapes, each of which plurality of tape maps points to all the user records of a respective one of the plurality of virtual magnetic tapes;repeating the first recording and the second recording as is required to do any of add, change and delete user records, and add, change or delete virtual magnetic tapes; while after each iteration of the first and the second recordingthird recording in a dedicated area of the optical disc a tape directory having at least pointer data pointing to the most recent one of each of the plurality of tape maps as is associated with each of the plurality of virtual magnetic tapes, the dedicated area of the optical disc ultimately coming to containing outdated tape directories and also a most currently updated tape directory, said outdated tape directories being identifiable from the most currently updated one tape directory because all tape directories are recorded seriatim in the dedicated area, and a last one such recorded, which is necessarily presently last in the dedicated area, is the most currently updated one tape directory;wherein the most currently updated one tape directory contains pointers to the most current tape map as is associated with each of the plurality of virtual magnetic tapes, and each most current tape map, in turn, contains pointers to all the most current ones of all the user records that are upon the associated virtual magnetic tape.