Handling zero fault tolerance events in machines where failure likely results in unacceptable loss

A computer program product for managing I/O requests to a storage array of storage devices in a machine having a processor node and device adaptor, the computer program product comprising a computer readable storage medium having computer readable program code embodied therein that is executable to perform operations, the operations comprising:

• in response to the device adaptor initiating a rebuild of data at the storage devices in the storage array, determining whether a remaining fault tolerance at the storage array comprises a non-zero fault tolerance that permits at least one further storage device of the storage devices to fail and still allow recovery of data stored in the storage array;
• and
• in response to determining that the remaining fault tolerance is a zero fault tolerance that does not permit at least one storage device to fail and allow recovery of data, sending, by the device adaptor, a message to the processor node to cause the processor node to initiate an emergency protocol to terminate a mission critical operation when the processor node is performing the mission critical operation.