Embedded directory method and record for direct access storage device (DASD) data compression
US5684986A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1995 |
| Grant date | Nov 4, 1997 |
| Priority date | — |
| Expiry date | Jun 7, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99945
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An embedded directory record and method are provided for maintaining directory information for compressed data on a direct access storage device (DASD). The embedded directory record includes a plurality of page entries, a plurality of exception region entries and a plurality of compression group statistics. Each page entry includes an allocated page length value and a number of used sectors value in the allocated page. The exception region entries include a page index and a bit map used for identifying exception sectors used. The compression group statistics include a total count of allocated sectors, a total count of the used sectors; and a total count of written pages. A starting page address for a requested page is identified beginning at a start of the page entries by summing the allocated page length values for each page up to the requested page to identify an offset value and combining the offset value with a predetermined logical block address. Reading and writing directory information utilize skip read and skip write operations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.