International Business Machines Corporation

Shiun Lee

Michael Joseph Corrigan

Lynn Keat Chung

Edwin C Grazier

Mark Gregory Manges

Mark Philip Piazza

Arlys Jean Leitzen

When a computer system is upgraded, such as by adding a more advanced processor chip and/or a new operating system, a different page size may be employed. The page size is altered for data previously stored in a storage medium such as a hard disk in the computer system, without removing all of the data from the medium and rewriting it. Data is stored in the medium in blocks or sectors which have headers defining the block. Also, tables define memory objects and segments, and locate virtual memory addresses in physical memory. The headers and/or tables can be changed without rewriting all of the data in the sectors or pages in physical memory, so the page size is changed to accommodate the new system components, without excessive burden on system hardware or undue expenditure of time. In an example, in changing from a CISC processor with a 512-byte page size to a RISC system with a 4K-byte page size, the segments are changed to always be of a size of an integral multiple of 4K, and 'extents' or subdivisions within a segment are changed to be multiples of 4K. Any excess space generated by these changes is zeroed. After alteration, the media (such as disks) can be accessed by either the CISC system or the new upgraded RISC system.

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Rochester, MN, United States of America

Shiun Lee