Data conversion in a multiprocessing system usable while maintaining system operations

摘要

In a multiprocessing system, data which is stored on an external storage media and shared by a plurality of processors is converted from an old format to a new format without bringing the multiprocessing system down. One processor at a time is provided the capability to view the data in the new format, while the other processors view the data in the old format. After all of the processors are capable of viewing the data in the new format, the data is converted from the old format to the new format and the data in the new format is stored on the external storage media. If for some reason the new format turns out to be unacceptable, procedures are also in place for falling back to the old format without disrupting system availability.