Detection and recovery of lost host enabled facilities

A non-transitory computer-readable medium having stored contents that, when executed, configure a computing system to perform a method for determining whether a control unit for an attached device has lost knowledge of a host enabled facility associated with the attached device, the method comprising:

• initiating a sequence of I/O instructions to the control unit that includes a first instruction to determine whether the control unit currently has knowledge of the host enabled facility and a second instruction providing knowledge of the host enabled facility by the control unit;
• based at least in part on one or more responses from the control unit to the sequence of I/O instructions, determining whether the control unit has transitioned from a first state in which the control unit does not have knowledge of the host enabled facility to a second state in which the control unit has knowledge of the host enabled facility;
• and
• based at least in part on a determination that the control unit has transitioned from the first state to the second state as a result of the sequence of I/O instructions, initializing one or more parameters for use with the host enabled facility, and otherwise preventing the initializing of the one or more parameters.

A system for determining whether a control unit for an attached device has lost knowledge of a host enabled facility associated with the attached device, comprising:

• one or more processors;
• and
• at least one memory, the memory including instructions that, upon execution by at least one of the one or more processors, cause the system to perform a method, the method including:
• initiating a sequence of I/O instructions to the control unit that includes a first instruction to determine whether the control unit currently has knowledge of the host enabled facility and a second instruction providing knowledge of the host enabled facility by the control unit;
• based at least in part on one or more responses from the control unit to the sequence of I/O instructions, determining whether the control unit has transitioned from a first state in which the control unit does not have knowledge of the host enabled facility to a second state in which the control unit has knowledge of the host enabled facility;
• and
• based at least in part on a determination that the control unit has transitioned from the first state to the second state as a result of the sequence of I/O instructions, initializing one or more parameters for use with the host enabled facility, and otherwise preventing the initializing of the one or more parameters.