gtpc3m19Concepts and Structures

Error Recovery

Errors can occur at any point during TPF operations. There can be programming errors, such as incorrect macro parameters, or hardware malfunctions, or a variety of unusual conditions. The levels of error are:

  1. Hardware malfunctions that are overcome by retrying the I/O operation. In this case, error statistics are recorded but the Entry is protected from the problem (for example, unit checks).
  2. An error detected by the system from which the programs related to an Entry may be able to recover. In this case, the ECB-controlled program regains control (for example, a record identification check).
  3. An error detected by the system from which the Entry cannot recover. In this case, the Entry is forced to exit (for example, an addressing exception generated by an ECB-controlled program).
  4. An error detected by the system that makes continued operation of the system inadvisable. This is called a catastrophic error; for example, an operation exception (programming error) within the control program. Such a failure is detected and handled by various components of the control program and may require a system restart.

The basic objectives for TPF system error processing are: