Log storage management in a data processing system using key-pointing

• Main Authors: Beaven, John Anthony, Mulholland, Martin
• Format: Patent
• Language: English
• Published: 05.08.2003

The present invention relates to log storage management in a data processing system with a key-pointing operation, and particularly to a mechanism for allocating storage for key-pointing. A data processing apparatus (, FIG. ) has a direct access non-volatile storage device () on which log records are stored in one or more log files. The processor () allocates storage for the log based on possible future requirements. The processor sets the maximum amount of new data that can be written to the log before a key-point operation is performed. When the maximum is reached a key-point is performed. As a result the maximum possible size of the active data written as part of the next key-point can be calculated and storage is allocated accordingly. Should storage become restricted such that the required storage cannot be allocated the data processing apparatus runs in a restricted mode during which the records that are written to the log are concerned with reducing the size of the active data and therefore the next key-point. In transaction processing this is achieved by: not starting new transactions; not allowing transactions to involve new participants; and only allowing transactions to complete.