COMPUTER COMMAND AND RESPONSE FOR DETERMINING THE STATE OF AN I/O OPERATION

• US 20090210573A1
• Filed: 02/14/2008
• Published: 08/20/2009
• Est. Priority Date: 02/14/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Sittmann, Gustav E., Kalos, Matthew J., Yudenfriend, Harry M., Huang, Catherine C., Flanagan, John R., Ricci, Louis W., Carlson, Scott M., Hathorn, Roger G., Njoku, Ugochukwu C., Casper, Daniel F., Riedy, Dale F.
• Granted Patent: US 8,108,570 B2
• Time in Patent Office: Days
• US Class Current: 710/19
• CPC Class Codes: G06F 13/12 using hardware independent of the central processor, e.g. channel or peripheral processor

Abstract

A state of an input/output (I/O) operation in an I/O processing system is determined. A request for performing the I/O operation is received from an I/O operating system at a channel subsystem and forwarded to a control unit controlling an I/O device for executing the I/O operation. After a predetermined amount of time passes without receiving indication from the control unit that the I/O operation is completed, an interrogation request is received at the channel subsystem from the I/O operating system for determining the state of the I/O operation. An interrogation command is sent from the channel subsystem to the control unit. A response is received from the control unit, the response indicates a state of the I/O device executing the I/O operation, a state of the control unit controlling the I/O device executing the I/O operation, and the state of the I/O operation being executed.

Claims

1. A computer program product for determining a state of an input/output (I/O) operation in an I/O processing system, comprising:

a tangible storage medium readable by a processing circuit and storing instructions for executing by the processing circuit for performing a method comprising;

receiving, at a channel subsystem, a request for performing the I/O operation from an I/O operating system;

forwarding the request from the channel subsystem to a control unit controlling an I/O device for executing the I/O operation;

after a predetermined amount of time passes without receiving indication from the control unit that the I/O operation is completed, receiving, at the channel subsystem, an interrogation request from the I/O operating system for determining the state of the I/O operation;

responsive to receipt of the interrogation request at the channel subsystem, sending an interrogation command from the channel subsystem to the control unit to determine the state of the I/O operation; and

receiving, at the channel subsystem, a response from the control unit indicating the state of the I/O operation, wherein the response includes information indicating a state of the I/O device executing the I/O operation, a state of the control unit controlling the I/O device executing the I/O operation, and the state of the I/O operation being executed.

2. The computer program product of claim 1, wherein the I/O operation is associated with a time period for completion, and the predetermined amount of time is less than the time period for completion.

3. The computer program product of claim 1, wherein the interrogation command includes information indicating why and when the interrogation command was sent.

4. The computer program product of claim 1, wherein the information included in the response indicating the state of the control unit indicates whether the control unit is busy, is performing a recovery operation, or is responding to other interrogation requests.

5. The computer program product of claim 1, wherein the information included in the response indicating the state of the I/O device indicates whether the I/O device is reserved by a path group, whether the control unit is in a long busy state, or whether the I/O device is performing a recovery process.

6. The compute program product of claim 1, wherein the information included in the response indicating the state of the I/O operations indicates whether an operation is present, executing, waiting for completion of another I/O operation, or waiting for performance of a device-dependent operation.

7. The computer program product of claim 1, wherein the information included in the response from the control unit indicates whether the I/O device is reserved by another I/O processing system.

8. An apparatus adapted for communicating with a control unit controlling an input/output (I/O) device for executing an I/O operation in an I/O processing system, the apparatus comprising:

a channel subsystem for communication with an I/O operating system and the control unit, the channel subsystem performing a method comprising;

receiving a request for performing the I/O operation from the I/O operating system;

forwarding the request to the control unit controlling the I/O device for executing the I/O operation;

after a predetermined amount of time passes without receiving indication from the control unit that the I/O operation is completed, receiving an interrogation request from the I/O operating system for determining a state of the I/O operation;

responsive to receipt of the interrogation request, sending an interrogation command to the control unit to determine the state of the I/O operation; and

receiving a response from the control unit indicating the state of the I/O operation, wherein the response includes information indicating a state of the I/O device executing the I/O operation, a state of the control unit controlling the I/O device executing the I/O operation, and the state of the I/O operation being executed.

9. The apparatus of claim 8, wherein the I/O operation is associated with a time period for completion, and the predetermined amount of time is less than the time period for completion.

10. The apparatus of claim 8, wherein the interrogation command includes information indicating why and when the interrogation command was sent.

11. The apparatus of claim 8, wherein the information included in the response indicating the state of the control unit indicates whether the control unit is busy, is performing a recovery operation, or is responding to other interrogation requests.

12. The apparatus of claim 8, wherein the information included in the response indicating the state of the I/O device indicates whether the I/O device is reserved by a path group, whether the control unit is in a long busy state, or whether the I/O device is performing a recovery process.

13. The apparatus of claim 8, wherein the information included in the response indicating the state of the I/O operations indicates whether an operation is present, executing, waiting for completion of another I/O operation, or waiting for performance of a device-dependent operation.

14. The apparatus of claim 8, wherein the information included in the response from the control unit indicates whether the I/O device is reserved by another I/O processing system.

15. A method for determining a state of an input/output (I/O) operation in an I/O processing system, comprising:

receiving, at a channel subsystem, a request for performing the I/O operation from an I/O operating system;

forwarding the request from the channel subsystem to a control unit controlling an I/O device for executing the I/O operation;

after a predetermined amount of time passes without receiving indication from the control unit that the I/O operation is completed, receiving, at the channel subsystem, an interrogation request from the I/O operating system for determining the state of the I/O operation;

responsive to receipt of the interrogation request at the channel subsystem, sending an interrogation command from the channel subsystem to the control unit to determine the state of the I/O operation; and

receiving, at the channel subsystem, a response from the control unit indicating the state of the I/O operation, wherein the response includes information indicating a state of the I/O device executing the I/O operation, a state of the control unit controlling the I/O device executing the I/O operation, and the state of the I/O operation being executed.

16. The method of claim 15, wherein the I/O operation is associated with a time period for completion, and the predetermined amount of time is less than the time period for completion.

17. The method of claim 15, wherein the interrogation command includes information indicating why and when the interrogation command was sent.

18. The method of claim 15, wherein the information included in the response indicating the state of the control unit indicates whether the control unit is busy, is performing a recovery operation, or is responding to other interrogation requests.

19. The method of claim 15, wherein the information included in the response indicating the state of the I/O device indicates whether the I/O device is reserved by a path group or another I/O processing system, whether the control unit is in a long busy state, or whether the I/O device is performing a recovery process.

20. The method of claim 15, wherein the information included in the response indicating the state of the I/O operations indicates whether an operation is present, executing, waiting for completion of another I/O operation, or waiting for performance of a device-dependent operation.