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Processing Multiple Records in a Disk Storage System

IP.com Disclosure Number: IPCOM000085331D
Original Publication Date: 1976-Mar-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Johnson, AB: AUTHOR

Abstract

Contemporary disk storage systems store or record data in one or more records on each track of the recording medium. Each record consists of two or three distinct fields separated by gaps.

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Processing Multiple Records in a Disk Storage System

Contemporary disk storage systems store or record data in one or more records on each track of the recording medium. Each record consists of two or three distinct fields separated by gaps.

The length of the field containing the actual data may be as short as one byte or as long as is allowed by the track capacity. Another field, the key field, which may or may not be present, can also vary in length from one byte up to a maximum of 255 bytes. Finally, the count field is always present, precedes the key and data fields, is fixed in length, and contains the length information of the key and data fields.

Thus, the records on a given track may vary in number, format (two or three fields), and length.

The operation of disk storage systems is structured around the processing of single records. A set of commands is provided, each of which permits an operation on either a part of a record or, at most, a single entire record. Thus, when retrieval of multiple records is desired, it is necessary to construct an entire set of commands to actually retrieve each record individually. To properly construct these commands, the number, format and length of the records must be known.

If this information is not known, the normal technique is to first read all of the count fields on a given track. From the length information within each count field, the series of single record commands is then constructed and executed. The requirement to read and analyze count fields prior to the actual reading of the records of interest seriously compromises the effectiveness of the disk storage system.

It is the object of this method to eliminate the need for this customized command chain, and thereby greatly improve the performance of multiple record retrieval. Thi...