Patent ID: 6983277
Filing Date: 2006-01-03
Classification: G06F,Y10S

Abstract:
1. A data processing unit including a database management system operating on an external storage unit provided with multiple storage areas for storing data, a multiple write mechanism allowing multiple writes of same data, a multiple write cancellation mechanism separating multi-written areas at a desired time to allow independent reading and writing as different control areas, and a physical copy mechanism that allows copying of data stored in the multiple storage areas, the data processing unit comprising: a first data synchronizing system for writing in a data cache, and then to the multiple storage areas in the external storage unit, unwritten data, and for delaying writing updated data to the multiple storage areas; a first data synchronization canceling system for restarting an update of the data under control of the first data synchronizing system; a second data synchronizing system for erasing all data in the data cache when all transactions in progress are completed, and for temporarily prohibiting access by a newly generated transaction while the erasing is occurring; and a second data synchronization canceling system for restarting data access under control of the second synchronizing system.