International Business Machines Corporation

Jack R Shedden

James Zu-Chia Teng

Shyh-Yee Wang

Hiromi Masuda

An integrated DBMS solution to recover primary site database based upon the maintenance of a shadow copy of the primary site's database data and logs at a remote site. Both the primary site DBMS and the remote site DBMS may support write-ahead logging protocol in which log records are written to a log data set before database updates are entered into the remote site storage. The remote site serves at least two functions: as a &ldquo;tracker&rdquo; DBMS and as a &ldquo;take-over&rdquo; DBMS. The tracker function maintains a shadow copy of the primary site's database data sets at the remote site. The multi-phased take-over function uses the shadow copies to update the remote site database data sets and substitutes them for primary site database data sets made unavailable by an unplanned disaster at the primary site.

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Morgan Hill, CA, United States of America

Jack R Shedden