Computer command and response for determining the state of an I/O operation

• US 7,904,605 B2
• Filed: 02/14/2008
• Issued: 03/08/2011
• Est. Priority Date: 02/14/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Kalos, Matthew J., Yudenfriend, Harry M., Huang, Catherine C., Flanagan, John R., Ricci, Louis W., Carlson, Scott M., Hathorn, Roger G., Sittmann, Gustav E., Njoku, Ugochukwu C., Casper, Daniel F., Riedy, Dale F.
• Primary Examiner(s): Kindred; Alford W
• Assistant Examiner(s): Unelus; Ernest
• Application Number:
  US12/030,975
• Publication Number:
  US 20090210572A1
• Time in Patent Office: 1,118 Days
• Field of Search: 710/19, 710/3, 710/4, 710/20, 711/167, 711/1, 711/100, 711/101
• US Class Current: 710/5
• CPC Class Codes: G06F 11/0745 in an input/output transactions management context input/output processing in general G06F13/00
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40
• CPC Class Codes: G06F 11/30 Monitoring

Abstract

A computer program product, apparatus, and method are provided for determining a state of an input/output (I/O) operation in an I/O processing system. A request from a channel subsystem is received at a control unit for performing the I/O operation. After a predetermined amount of time passes without the I/O operation completing, an interrogation request is received from the channel subsystem at the control unit for determining the state of the I/O operation. A response is sent from the control unit to the channel subsystem indicating the state of the I/O operation in response to the interrogation request. The response also includes information regarding a state of an I/O device executing the I/O operation and information indicating a state of the control unit controlling the I/O device executing the I/O operation.

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 a request from a channel subsystem at a control unit for performing the I/O operation, the channel subsystem configured to send the request using a transport control word (TCW), the request having an associated time period for completion of the I/O operation;

receiving an interrogation request from the channel subsystem at the control unit at a point in time prior to the expiration of the associated time period and absent completion of the I/O operation, the interrogation request for determining the state of the I/O operation, and sent from the channel subsystem within a threshold of the expiration of the associated time period, wherein the interrogation request includes an interrogate device command word (DCW), and the interrogate DCW is received via a transport command control block (TCCB); and

sending a response from the control unit to the channel subsystem in response to the interrogation request, wherein the response includes information indicating the state of the I/O operation, a state of an I/O device performing the I/O operation and a state of the control unit.

2. The computer program product of claim 1, wherein the interrogation request includes a request to cancel the I/O operation.

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

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

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

6. The computer program product of claim 1, wherein the information included in the response from the control unit indicates whether the I/O device was reserved for another system.

7. An apparatus adapted for communicating with a channel subsystem, comprising:

a control unit for controlling execution of an input/output (I/O) operation by an I/O device, the control unit configured to communicate with the channel subsystem, the control unit configured to perform a method comprising;

receiving a request from the channel subsystem for performing the I/O operation, the channel subsystem configured to send the request using a transport control word (TCW), the request having an associated time period for completion of the I/O operation;

receiving an interrogation request from the channel subsystem at a point in time prior to the expiration of the associated time period and absent completion of the I/O operation, the interrogation request for determining a state of the I/O operation, and sent from the channel subsystem within a threshold of the expiration of the associated time period, wherein the interrogation request includes an interrogate device command word (DCW), and the interrogate DCW is received via a transport command control block (TCCB); and

sending a response to the channel subsystem in response to the interrogation request, wherein the response includes information indicating the state of the I/O operation, a state of the I/O device performing the I/O operation and a state of the control unit.

8. The apparatus of claim 7, wherein the interrogation request includes a request to cancel the I/O operation.

9. The apparatus of claim 7, wherein the interrogation request includes information indicating why and when the interrogation request was sent.

10. The apparatus of claim 7, 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, and 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.

11. The apparatus of claim 7, wherein the information included in the response indicating the state of the I/O operation indicates whether the I/O operation is present, executing, waiting for completion of another I/O operation, or waiting for performance of a device-dependent operation.

12. The apparatus of claim 7 wherein the information included in the response from the control unit indicates whether the I/O device was reserved for another system.

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

receiving a request from a channel subsystem at a control unit for performing the I/O operation, the channel subsystem configured to send the request using a transport control word (TCW), the request having an associated time period for completion of the I/O operation;

receiving an interrogation request from the channel subsystem at the control unit at a point in time prior to the expiration of the associated time period and absent completion of the I/O operation, the interrogation request for determining the state of the I/O operation, and sent from the channel subsystem within a threshold of the expiration of the associated time period, wherein the interrogation request includes an interrogate device command word (DCW), and the interrogate DCW is received via a transport command control block (TCCB); and

sending a response from the control unit to the channel subsystem in response to the interrogation request, wherein the response includes information regarding the state of the I/O operation, a state of an I/O device performing the I/O operation and a state of the control unit.

14. The method of claim 13, wherein the interrogation request includes a request to cancel the I/O operation.

15. The method of claim 13, wherein the interrogation request includes information indicating why and when the interrogation request was sent.

16. The method of claim 13, wherein the information included in the response indicating the state of control unit indicates whether the control unit is busy, is performing a recovery operation, or is responding to other interrogation requests, and 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.

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