Processing of data to suspend operations in an input/output processing log-out system

• US 7,840,718 B2
• Filed: 02/14/2008
• Issued: 11/23/2010
• 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.
• Primary Examiner(s): CHEN, ALAN S
• Application Number:
  US12/031,021
• Publication Number:
  US 20090210585A1
• Time in Patent Office: 1,013 Days
• Field of Search: None
• US Class Current: 710/5
• 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:

sending by the channel subsystem, a Process Log-in (PRLI) message to the control unit, the PRLI message comprising a maximum time for suspension of input/output operations that the channel subsystem can allow in an Initiation Delay Time field in a Process Log-out (PRLO) from the control unit;

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 Initiation Delay Time field in 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 PRLI message is configured to establish service parameters between the channel subsystem and the control unit, and the PRLO message is configured to invalidate existing service parameters between the channel subsystem and the control unit.

4. 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.

5. 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.

6. The computer program product of claim 1, the method further comprising:

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.

7. The computer program product of claim 1, wherein the PRLI message is configured to establish service parameters between the channel subsystem and the control unit, wherein the service parameters comprise a type code field, a maximum initiation Delay Time field and a flags field, wherein the PRLI message comprises:

a protocol type indicated by a value in the type code field of the PRLI message, wherein a value of hex “

1B”

represents a Fibre Channel Single Byte Protocol;

the maximum time for suspension of input/output operations that the channel can allow in the Initiation Delay Time field in a process Logout (PRLO) message from the control unit indicated by a value in the Maximum Initiation Delay Time field of the PRLI message; and

a mode supported b a sender of the PRLI message the mode indicated b the flags field of the PRLI message, the flags field comprising a mode bit, the mode bit being 1 indicating the sender supports both a command mode and a transport mode, the mode bit being 0 indicating the sender supports the command mode but not the transport mode.

8. 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.

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

a channel subsystem of a host computer system for communicating with a control unit capable of commanding and determining status of an I/O device, the control unit configured to communicate with the channel subsystem, the apparatus configured to perform;

sending by the channel subsystem, a Process Log-in (PRLI) message to the control unit, the PRLI message comprising a maximum time for suspension of input/output operations that the channel subsystem can allow in an Initiation Delay Time field in a Process Log-out (PRLO) from the control unit;

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 Initiation Delay Time field in 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.

10. The apparatus of claim 9, 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.

11. The apparatus of claim 9, wherein suspending comprises at least one of terminating and completing input/output operations pending between the channel subsystem and the control unit.

12. The apparatus of claim 9, wherein the PRLI message is configured to establish service parameters between the channel subsystem and the control unit and the PRLO message is configured to invalidate existing service parameters between the channel subsystem and the control unit.

13. The apparatus of claim 9, wherein suspending comprises waiting a second period of time, and thereafter sending a PRLO accept message to the control unit.

14. The apparatus of claim 9, wherein the apparatus is configured to further perform:

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.

15. The apparatus of claim 9, wherein the PRLI message is configured to establish service parameters between the channel subsystem and the control unit, wherein the service parameters comprise a type code field, a maximum initiation Delay Time field and a flags field, wherein the PRLI message comprises:

a protocol type indicated by a value in the type code field of the PRLI message, wherein a value of hex “

1B”

represents a Fibre Channel Single Byte Protocol;

the maximum time for suspension of input/output operations that the channel can allow in the Initiation Delay Time field in a process Logout (PRLO) message from the control unit indicated by a value in the Maximum Initiation Delay Time field of the PRLI message; and

a mode supported by a sender of the PRLI message, the mode indicated by the flags field of the PRLI message, the flags field comprising a mode bit, the mode bit being 1 indicating the sender supports both a command mode and a transport mode, the mode bit being 0 indicating the sender supports the command mode but not the transport mode.

16. The apparatus of claim 9, 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.

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

sending by the channel subsystem, a Process Log-in (PRLI) message to the control unit, the PRLI message comprising a maximum time for suspension of input/output operations that the channel subsystem can allow in an Initiation Delay Time field in a Process Log-out (PRLO) from the control unit;

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 Initiation Delay Time field in 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.

18. The method of claim 17, further comprising:

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.

19. The method of claim 17, 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.

20. The method of claim 17, wherein the PRLI message is configured to establish service parameters between the channel subsystem and the control unit, and the PRLO message is configured to invalidate existing service parameters between the channel subsystem and the control unit.

21. The method of claim 20, wherein the PRLI message is configured to establish service parameters between the channel subsystem and the control unit, wherein the service parameters comprise a type code field, a maximum initiation Delay Time field and a flags field, wherein the PRLI message comprises:

a protocol type indicated by a value in the type code field of the PRLI message, wherein a value of hex “

1B”

represents a Fibre Channel Single Byte Protocol;

the maximum time for suspension of input/output operations that the channel can allow in the Initiation Delay Time field in a process Logout (PRLO) message from the control unit indicated by a value in the Maximum Initiation Delay Time field of the PRLI message; and

a mode supported by a sender of the PRLI message, the mode indicated by the flags field of the PRLI message, the flags field comprising a mode bit, the mode bit being 1 indicating the sender supports both a command mode and a transport mode, the mode bit being 0 indicating the sender supports the command mode but not the transport mode.