Bmc Software, Inc.

Linda S Ball

Thomas G Price

Stanley James Dee

Kenneth M McDonald

Michael S Murley

William R Cunningham

Carla C Birk

Stanley D Dee

Shawn B Wikle

Techniques to create physically and transactionally consistent copies of one or more database objects without impacting the availability of the target database objects are described. In one technique, a consistent copy is created as of the time a copy utility is executed. In another technique, a consistent copy is created as of an arbitrary specified time. This approach modifies a prior copy to bring it 'up-to-date.' In yet another technique, a consistent copy is created by starting with a current snapshot of the target database objects and selectively removing updates from it back to a user specified arbitrary point-in-time. Each of the described techniques generate consistent copies of the target database objects without blocking users from accessing the target objects during the copy operation.

Unobtrusive point-in-time consistent copies

Techniques to provide run-time access to a database image through a target database management system (DBMS) are described. An empty database in the target DBMS (the 'target database') is created having substantially the same schema as the database image. At run-time, queries directed to the target database are intercepted and redirected to the database image. Information returned in response to the redirected query is modified so that internal database identifiers retrieved from the database image are replaced with like database identifiers associated with the target database management system. Thus, run-time access to database image content is provided without the need to load the database image's data content into a target database.

Run-time access techniques for database images

A computer program operating in accordance with the invention monitors WRITE requests issued by a data-writing program that accesses data sets, e.g., for updating the data sets, and READ requests issued by a data-reading program that accesses data sets, e.g., for copying the data. While a series of READ requests (e.g., a data set copying operation) is in progress, the computer program monitors all WRITE requests issued for the data set in question by the data-writing program. If the data-reading program has not yet read the data portion (e.g., a data page) that is to be updated, the computer program selectively creates a cached image of the data portion as it existed at the beginning of the series of READ requests and delivers the cached image to the data-reading program, thereby reducing the potential for internal inconsistencies in the copied data. The computer program advantageously permits such caching to be performed without the need for specialized caching hardware.

Method of creating an internally consistent copy of an actively updated data set without specialized caching hardware

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Austin, TX, United States of America

Linda S Ball