Users of Conventional file recovery mechanisms are recommended to avoid the use of the 'implicit' unlocking policy to avoid the possibility of corrupting data files.

The VME default unlocking policy, and the most commonly used, is explicit unlocking. There are no current problems with this locking policy.

The data corruption may occur where concurrent users are updating the same blocks or overflow chains and recovery is invoked by one user. This should be a rare circumstance as current recomendations suggest that read-only applications use the implicit unlocking policy. Its main use is to allow concurrent batch access to files being updated with TPMS services.

The default unlocking policy on a newly created file is explicit. Implicit locking may be defined temporarily using SET_FILE_OPTIONS or permanantly via DESCRIBE_FILE_USAGE. Current files can be checked using DISPLAY_FILE_DETAILS.

SKE 79258 documents this problem.

If you would like to discuss the possible effects further please log a call in the normal way.