Method of determining and storing indexing data on a sequential data storage medium for supporting random access of data files stored on the medium

摘要

A format structure for storing retrievably encoded data on a recording medium is disclosed. A start field for indicating the start of a data file is provided. Immediately following the start field there provided an index field for storing indexing data respecting the data file. In the index field a sequence of one or more positions of other start fields leading in one direction from a current position on the medium toward one end of the medium is stored. Immediately following the index field there is a field for storage data, which forms the data file. A method for storing encoded data on a storage medium is also disclosed. The last file stored on the medium is located. The index field of the last stored file is then retrieved. The index field associated therewith is duplicated for later use. The system then moves the storage medium to the end of the last stored file. At the current position of the medium a filemark is inserted. Then a final leaf block is inserted having a new entry containing the entry key of the new file and the current position of the medium. The indexing data is stored immediately following the filemark and finally the encoded data is stored immediately following the indexing data.