Error handling

If errors occur in device operation or device requests and in I/O operations, FDDRL attempts recovery. If this fails, the operator receives a message that must be answered; otherwise FDDRL aborts the FDDRL job.

Messages requiring an operator response

These messages include:

• Errors in device/volume allocation

• Unrecoverable input/output errors

Depending on the situation, FDDRL offers the following response options:

• Repeat (RETRY)
  e.g. in the case of input/output errors, device INOP

• Skip (CONTINUE)
  e.g. in the case of disk input errors (parity, block length, undefined) and unreadable user labels, i.e. UTLs (user trailer labels), EOF (end-of-file labels) or EOV (end-of-volume labels)

• Skip the current error and all future errors (CONTINUE ALWAYS)
  e.g. in the case of disk and tape input errors (parity)

• Restart (RESTART)
  e.g. in the case of input/output errors which may be due to device problems that might be remedied by using a different device.
  For disks, the volume is released and requested again; then input/output is repeated. For MTC, the volume is requested again, allocated and then rewritten from the beginning.

• Abort FDDRL jobs (TERMINATE)
  The FDDRL job is aborted. The allocated devices are released and the program terminates. In the log the abortion is indicated by the termination code.