WO1993025956B1

WO1993025956B1 - Method and apparatus for writing files on nonerasable storage medium

Info

Publication number: WO1993025956B1
Application number: PCT/US1993/005414
Authority: WO
Filing date: 1993-06-07
Publication date: 1994-02-03

Abstract

Method and apparatus for writing data to files from a computer system to a Write Once Read Many (WORM) Disc medium which results in a creation of an ISO 9660 standard disc is disclosed. The method and apparatus each efficiently manages writes to WORM medium in the creation of a file structure that conforms to ISO standard 9660 which governs management of CD-ROM disc files. The method and apparatus are efficient both in terms of the time required to perform such writes and in the amount of medium consumed as overhead. In addition, the invention provides a method and apparatus for writing to WORM disc in which there is a high degree of confidence that the information written is indelible.

Claims

AMENDED CLAIMS

[received by the International Bureau on 29 November 1993 (29.11.93); original claims 1-4 deleted; remaining claims unchanged (6 pages)]

5. A method of writing to an write once storage medium, said method comprising:

initializing said write once storage medium for I/O actions;

reading medium management information from said write once storage medium;

constructing file management information using said medium management information;

managing data recorded on said write once storage medium as a series of files, said files having a format used for a read only optical disc; and

freezing said data on said write once storage medium which results in said write once storage medium having a read only optical disc format.

6. The method of claim 5 wherein said managing includes writing said data to said write once storage medium in a read only optical disc format.

7. The apparatus of claim 5 wherein wherein said managing includes updating said file management information and said medium management information each time a file is completed on said write once storage medium. 8. The method of claim 5 wherein said read only optical disc format is ISO 9660 standard format.

9. The system of claim 6 wherein said medium management information includes Directory Audit records .

10. The method of claim 5 wherein said initializing comprises the steps of:

(a) verifying that said write once storage medium is not in a read only state;

(b) constructing a partial read only volume descriptor for said write once storage medium;

(c) writing said partial read only volume descriptor to an area of said write once storage medium which is compatible with said read only disc format;

11. The method of claim 10 wherein said partial read only volume descriptor conforms to the ISO 9660 standard.

12. The method of claim 10 wherein step (a) comprises the step of verifying that an ISO 9660 standard Primary Volume Descriptor is not present on the write once storage medium in conformance with the ISO 9660 standard.

13. The method of claim 5 wherein said freezing comprises the steps of:

constructing a complete read only disc format directory from said file management directory; writing said complete read only disc format directory to an area of said write once storage medium which is compatible with said read only disc format;

14. The method of claim 13 wherein said read only disc format conforms to the ISO 9660 standard.

15. The method of claim 14 which further includes the steps of: constructing a complete ISO 9660 Primary Volume Descriptor; and

writing said Primary Volume Descriptor to said write once storage medium in conformance with the ISO 9660 standard.

16. The method of claim 9 wherein said constructing of said file management information comprises the steps of :

(a) extracting the next block of data from said write once storage medium management information;

(b) determining if said block is a Directory Audit record and, if so, the type of said Directory Audit record;

(c) verifying that the size of the area referenced by said Directory Audit record is consistent with any previously read Directory Audit record references to said area if said Directory Audit record is a file type, a potential file type, or a discard type Directory Audit record;

(d) adding a node to said file management information if said Directory Audit record is not a freeze type Directory Audit record; (e) repeating the steps a, b, c, and d if said block is a file type, a potential file type or a discard type Directory Audit record;

(f) performing a freeze action if said block is a freeze type Directory Audit record;

17. The method of claim 16 wherein said file management information contains the information necessary to create a ISO 9660 standard file directory.

18. The method of claim 16 which further includes the steps of:

(g) if no freeze type Directory Audit records have been encountered and no Directory Audit records remain to be read, verifying that the area immediately following the last valid data area is virgin medium;

(h) if said area immediately following said last valid data area is not virgin medium, performing a search for the end of the non-blank area above said last valid data area written, said search ending if the end of the area available for data is encountered without a virgin area being found;

(i) creating a discard type Directory Audit record describing said non-blank area detected by said search; and

( j ) writing said discard type Directory Audit record to said medium management information c said write once storage medium.

19. The method of claim 16 which further includes the steps of: (g) if no freeze type Directory Audit records have been encountered and no Directory Audit records remain to be read, verifying that the area immediately following the last valid data area is virgin medium;

(h) if said area immediately following said last valid data area is not virgin medium, performing a search for the end of the non-blank area above said last valid data area written, said search ending if the end of the area available for data is encountered without a virgin area being found; and

(i) establishing said non-blank area detected by said search as a pending protected file if the last Directory Audit record read from said medium managemment information was a potential file type Directory Audit record.

20. The method of claim 9 wherein said writing of said data to one of said files comprises the steps of:

determining the length of said data to be written;

determining if sufficient space is available on said write once storage medium to accomplish said write;

selecting a destination area on said write once storage medium for the data to be written if the result of the previous step indicated that sufficient space is available;

transferring said data to said destination area on said write once storage medium; constructing a Directory Audit record describing said one of said files;

writing said Directory Audit record to said medium management information on said write once storage medium.

21. The method of claim 20 further including the step of:

constructing a potential file type Directory Audit record before any data is transferred to said write once storage medium for said one of said files; and

writing said potential file Directory Audit record to said medium management information on said write once storage medium.

22. The method of claim 20 wherein the area comprising said data written on said write once storage medium grows linearly toward the area for said medium management information written on said write once storage medium.