PROCESSING OF DATA TO SUSPEND OPERATIONS IN AN INPUT/OUTPUT PROCESSING LOG-OUT SYSTEM

• US 20090210585A1
• 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: Kalos, Matthew J., Yudenfriend, Harry M., Huang, Catherine C., Flanagan, John R., Ricci, Louis W., Carlson, Scott M., Bendyk, Mark P., Hathorn, Roger G., Sittmann, Gustav E., Casper, Daniel F.
• Granted Patent: US 7,840,718 B2
• Time in Patent Office: Days
• US Class Current: 710/48
• CPC Class Codes: G06F 13/124 where hardware is a sequential transfer control unit, e.g. microprocessor, peripheral processor or state-machine

Abstract

A computer program product, an apparatus, and a method for processing communications between a control unit and a channel subsystem in an input/output processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes: sending a Process Log-out (PRLO) message from the control unit to the channel subsystem, the message requesting suspension of input/output operations between the control unit and the channel subsystem for a period of time, the period of time being defined by the PRLO message; responsive to the PRLO message, suspending by the channel all input/output operation messages for the period of time, wherein suspending comprises stopping input/output operation messages during the period of time; and responsive to an expiration of the period of time, sending a Process Log-in (PRLI) message from the channel subsystem to the control unit to re-initiate an operating environment between the channel subsystem and the control unit.

Claims

1. A computer program product for processing communications between a control unit and a channel subsystem in an input/output processing system, comprising a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising:

the channel subsystem receiving a Process Log-out (PRLO) message from the control unit, the message requesting suspension of input/output operations between the control unit and the channel subsystem for a period of time, the period of time being defined by the PRLO message;

responsive to the PRLO message, suspending by the channel all input/output operation messages for the period of time, wherein suspending comprises stopping input/output operation messages during the period of time; and

responsive to an expiration of the period of time, sending a Process Log-in (PRLI) message from the channel subsystem to the control unit to re-initiate an operating environment between the channel subsystem and the control unit.

2. The computer program product of claim 1, wherein the control unit, prior to sending the PRLO message, performs at least one of:

sending at least one busy signal to the channel subsystem in response to at least one request for execution of an input/output operation, completing pending input/output operations, and terminating pending input/output operations.

3. The computer program product of claim 1, wherein the PRLO message comprises a data setting in a field of the PRLO message that defines the period of time.

4. The computer program product of claim 3, wherein the field is an initiation delay time field.

5. The computer program product of claim 1, wherein suspending comprises at least one of terminating and completing input/output operations pending between the channel subsystem and the control unit.

6. The computer program product of claim 1, wherein suspending comprises waiting a second period of time, and thereafter sending a PRLO accept message to the control unit.

7. The computer program product of claim 1, wherein sending the PRLI message comprises:

sending an identification message from the channel subsystem to the control unit to determine whether the control unit supports a PRLI/PRLO protocol; and

responsive to receiving an identification message response indicating that the control unit supports the PRLI/PRLO protocol, sending the PRLI message to the control unit.

8. The computer program product of claim 1, wherein the PRLI message comprises service parameters for the channel subsystem and the control unit.

9. The computer program product of claim 1, wherein sending the PRLI message comprises:

awaiting a PRLI accept message from the control unit; and

responsive to receiving the PRLI accept message, initiating new input/output operations.

10. An apparatus for processing communications in an input/output processing system, comprising:

a channel subsystem of a host computer system, adapted to communicate with a control unit capable of commanding and determining status of an I/O device, in communication with the channel subsystem, the apparatus performing;

the channel subsystem receiving a Process Log-out (PRLO) message from the control unit, the message requesting suspension of input/output operations between the control unit and the channel subsystem for a period of time, the period of time being defined by the PRLO message;

responsive to the PRLO message, suspending by the channel all input/output operation messages for the period of time, wherein suspending comprises stopping input/output operation messages during the period of time; and

responsive to an expiration of the period of time, sending a Process Log-in (PRLI) message from the channel subsystem to the control unit to re-initiate an operating environment between the channel subsystem and the control unit.

11. The apparatus of claim 10, wherein the control unit, prior to sending the PRLO message, performs at least one of:

sending at least one busy signal to the channel subsystem in response to at least one request for execution of an input/output operation, completing pending input/output operations, and terminating pending input/output operations.

12. The apparatus of claim 10, wherein suspending comprises at least one of terminating and completing input/output operations pending between the channel subsystem and the control unit.

13. The apparatus of claim 10, wherein the PRLO message comprises a data setting in a field of the PRLO message that defines the period of time.

14. The apparatus of claim 10, wherein suspending comprises waiting a second period of time, and thereafter sending a PRLO accept message to the control unit.

15. The apparatus of claim 10, wherein sending the PRLI message comprises:

sending an identification message from the channel subsystem to the control unit to determine whether the control unit supports a PRLI/PRLO protocol; and

responsive to receiving an identification message response indicating that the control unit supports the PRLI/PRLO protocol, sending the PRLI message to the control unit.

16. The apparatus of claim 10, wherein the PRLI message comprises service parameters for the channel subsystem and the control unit.

17. The apparatus of claim 10, wherein sending the PRLI message comprises:

awaiting a PRLI accept message from the control unit; and

responsive to receiving the PRLI accept message, initiating new input/output operations.

18. A method of processing communications between a control unit and a channel subsystem in an input/output processing system, the method comprising:

the channel subsystem receiving a Process Log-out (PRLO) message from the control unit, the message requesting suspension of input/output operations between the control unit and the channel subsystem for a period of time, the period of time being defined by the PRLO message;

responsive to the PRLO message, suspending by the channel all input/output operation messages for the period of time, wherein suspending comprises stopping input/output operation messages during the period of time; and

responsive to an expiration of the period of time, sending a Process Log-in (PRLI) message from the channel subsystem to the control unit to re-initiate an operating environment between the channel subsystem and the control unit.

19. The method of claim 18, wherein sending the PRLI message comprises:

sending an identification message from the channel subsystem to the control unit to determine whether the control unit supports a PRLI/PRLO protocol; and

responsive to receiving an identification message response indicating that the control unit supports the PRLI/PRLO protocol, sending the PRLI message to the control unit.

20. The method of claim 18, wherein sending the PRLI message comprises:

awaiting a PRLI accept message from the control unit; and

responsive to receiving the PRLI accept message, initiating new input/output operations.