Abstract: A method of checking a large and/or replicated databases includes forming a position sensitive checksum for each entry of the database to be used in the check. The checksums are then exclusive Ored with one another to form a first database checksum. Periodically, the checksums are again created from each of the entries of the check and a second database checksum formed and compared to the first for a match that indicate checked entries of the database have not changed. In another embodiment, a modification to one of the check entries may be provided, accompanied by a master checksum indicative of what the first checksum should be after the entry is modified. The database entry is modified, and a position checksum value for the entry as modified is created.

Abstract: An expert system for determining the likelihood of failure of a unit in a computer system. The operating system of the computer system maintains a log of the errors occurring for each unit in the computer system. If a predetermine number of errors have been entered in the log for a specific unit, the expert system retrieves the error entries relating to that unit and processes them to determine whether a failure is likely to occur. In this, the processing performed by the expert system is arranged so that tests relating to components of increasing particularity, and decreasing generality, are performed after the tests relating to more general components.

Abstract: An expert system for determining the likelihood of failure of a unit in a computer system. The operating system of the computer system maintains a log of the errors occurring for each unit in the computer system. If a predetermined number of errors have been entered in the log for a specific unit, the expert system retrieves the error entries relating to that unit and processes them to determine whether a failure is likely to occur. In this, the processing performed by the expert system is arranged so that tests relating to components of increasing particularity, and decreasing generality, are performed after the tests relating to more general components.