Narrowing reposition search area in a tape directory region
AssigneeInternational Business Machines Corporation
InventorsSetsuko Masuda, Tsuyoshi Miyamura
Life of this patent
Estimating the term…
Abstract
In one general embodiment, a method includes narrowing down a number of data sets to be searched in an HRTD (High Resolution Tape Directory) area for a target record based at least in part on a ratio of: a number of records from a beginning of the HRTD area to the target record, and a total number of records in the HRTD area having the target record. A physical position range in the HRTD area where the narrowed number of data sets physically exist is calculated based on a linear density of a tape drive specification. A magnetic tape having the HRTD area is repositioned to a starting data set in the calculated physical position range. The narrowed range of data sets is read starting at the starting data set.
Claims20
A method, comprising:
- narrowing down a number of data sets to be searched in an HRTD (High Resolution Tape Directory) area for a target record based at least in part on a ratio of:
- a number of records from a beginning of the HRTD area to the target record, and
- a total number of records in the HRTD area having the target record;
- calculating a physical position range in the HRTD area where the narrowed number of data sets physically exist based on a linear density of a tape drive specification;
- repositioning a magnetic tape having the HRTD area to a starting data set in the calculated physical position range;
- and
- reading the narrowed range of data sets starting at the starting data set.
A computer program product comprising:
- one or more computer readable storage media;
- and
- program instructions stored on the one or more storage media to perform operations comprising:
- narrowing down a number of data sets to be searched in an HRTD (High Resolution Tape Directory) area for a target record based at least in part on a ratio of:
- a number of records from a beginning of the HRTD area to the target record, and
- a total number of records in the HRTD area having the target record;
- calculating a physical position range in the HRTD area where the narrowed number of data sets physically exist based on a linear density of a tape drive specification;
- repositioning a magnetic tape having the HRTD area to a starting data set in the calculated physical position range;
- and
- reading the narrowed range of data sets starting at the starting data set.
An apparatus, comprising:
- a controller configured to perform operations comprising:
- narrowing down a number of data sets to be searched in an HRTD (High Resolution Tape Directory) area for a target record based at least in part on a ratio of:
- a number of records from a beginning of the HRTD area to the target record, and a total number of records in the HRTD area having the target record,
- calculating a physical position range in the HRTD area where the narrowed number of data sets physically exist based on a linear density of a tape drive specification,
- repositioning a magnetic tape having the HRTD area to a starting data set in the calculated physical position range, and
- reading the narrowed range of data sets starting at the starting data set;
- and
- a drive mechanism for passing the tape over a magnetic head.
Dependencies are inferred from the claim text.