Patent ID: 6189001
Filing Date: 2001-02-13
Classification: G06F,G11B,Y10S

Abstract:
A process for the storage and retrieval of data on a tape system including a tape drive with on-line tape storage and off-line retrieval, the process being carried out by a database controller, a data processor and a tape system controller, the process comprising the steps of:setting up a database structure including a single volume type dataset for a plurality of data objects containing one or more variable length logical records;creating a hierarchy of storage levels based on perceived levels of activity for data objects written to the database to provide separate specific storage levels;allocating a tape to a specific storage level;allocating an appropriate proportion of the storage capacity of that tape for storage of objects at that specific storage level; andsetting up an index file for the database comprising a single index control record with tape system initialisation data for each object;on receiving an object storage request for the system carrying out the steps of:allocating a storage level to the object;assigning the object to an appropriate tape for that storage level;creating a new record header within the tape for that object, the header including a primary key, a storage date and at least storage level information;writing the object to the tape in sequence after the record header;entering the record header and associated tape position information on the index file;over time re-assessing the storage level assigned to the object;allocating a new storage level to the object as a result of a re-assessment;altering the record header for the object within the tape and the index file to reflect the new storage level; andhaving the tape system controller handle the object in the appropriate manner within the tape system for that storage level; andon receiving a data retrieval request carrying out the steps of:addressing the index files with the primary key and the storage date and accessing the relevant tape and tape position information; andtransmitting read instructions to the tape system.