An MIH record is recorded on the logrec data set for a missing
interruption on a device, except teleprocessing (TP) devices attached
through a 3704 or 3705 in EP mode, or expiration of the I/O timing
limit for an I/O request. The system, invoked at time intervals specified
by the user or by the system, invokes the missing interruption handler
(MIH) to check the unit control blocks (UCB) for pending conditions. If MIH detects that the time limit for an I/O request has
been exceeded, it considers that interrupt to be missing and does
the following:
- Attempts to clear the failing device or subchannel.
- Issues a message to the system operator.
- Obtains information about the missing interruption (such as the
device number, recovery actions, and time interval used by MIH) to
build an MIH record.