Method and apparatus for emulating read/write file system on a write-once storage disk
DCFirst Claim
1. A method for emulating an erasable storage medium using a non-erasable optical disk, wherein the optical disk includes a writing area formed in a spiral track, the method comprising:
- writing a plurality of data files in the writing area, wherein a first data file is written from a first end of the spiral track, a second data file is written from the end of the first data file on the spiral track, and so on for remaining data files;
generating a system sector for the data files, wherein the system sector identifies, for each data file, its location in the writable area and its size;
writing the system sector in the writable area, wherein the system sector is written from the remaining end of the spiral track;
generating an updated system sector whenever there is a change in the data files stored on the writable area, wherein the updated system sector identifies only, for each changed data file, its location in the writable area and its size, the unchanged data files being identified by the system sector; and
writing the updated system sector in the writable area, wherein the updated system sector is written from the end of the system sector on the spiral track.
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Abstract
A method and apparatus for storing, updating, adding, deleting, and locating file system objects on a WORM storage medium, wherein information can be written to, but not erased from, the storage medium. The WORM storage medium has a writeable area that includes a system area and a data area. The system area includes system information regarding the file system objects on the storage medium. A system sector is written starting at one end of the system area, while the content of the file system objects is written in the data area starting at another end of the writeable area. When a change is made to the file system objects in the writeable area, an updated system sector is generated that replaces the previous file system information for those modified file system objects. Since the previous system sector is not erasable, the updated system sector is written in a location in the system area where it will be read before any previous system sectors. The updated system sector overrides file system information in previously generated system sectors. The information required to access all the file system objects on the storage medium may be included in the updated system sector, or in the updated system sector along with one or more of the previously generated system sectors.
80 Citations
12 Claims
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1. A method for emulating an erasable storage medium using a non-erasable optical disk, wherein the optical disk includes a writing area formed in a spiral track, the method comprising:
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writing a plurality of data files in the writing area, wherein a first data file is written from a first end of the spiral track, a second data file is written from the end of the first data file on the spiral track, and so on for remaining data files; generating a system sector for the data files, wherein the system sector identifies, for each data file, its location in the writable area and its size; writing the system sector in the writable area, wherein the system sector is written from the remaining end of the spiral track; generating an updated system sector whenever there is a change in the data files stored on the writable area, wherein the updated system sector identifies only, for each changed data file, its location in the writable area and its size, the unchanged data files being identified by the system sector; and writing the updated system sector in the writable area, wherein the updated system sector is written from the end of the system sector on the spiral track. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A write-once read-many (WORM) optical disk, comprising:
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a writeable area on the optical disk, wherein the writable area is formed in a spiral track, the spiral track forming a data area starting at a first end of the spiral track and extending towards the remaining end and forming a system sector starting at the remaining end and extending towards the first end, wherein the data area comprises a plurality of data files and the system sector identifies the location and size of the data files;
the writable area including;an updated system sector for accessing only updated data files, the updated system sector being written in the writable area starting from the end of the system sector towards the data area along the spiral track, the updated system sector identifying the location and size of the updated data files, the information for accessing the data files that were not updated being stored in the system sector. - View Dependent Claims (10, 11, 12)
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Specification