EARLY TERMINATION OF AN I/O OPERATION IN AN I/O PROCESSING SYSTEM

• US 20090210580A1
• 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: Njoku, Ughochukwu C., Kalos, Matthew J., Yudenfriend, Harry M., Huang, Catherine C., Flanagan, John R., Ricci, Louis W., Carlson, Scott M., Bendyk, Mark P., Casper, Daniel F.
• Granted Patent: US 8,176,222 B2
• Time in Patent Office: Days
• US Class Current: 710/32
• CPC Class Codes: G06F 13/122 where hardware performs an I/O function other than control of data transfer

Abstract

A computer program product, apparatus, and method for handling early termination of an I/O operation at a channel subsystem in an I/O 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 receiving a request to terminate an I/O operation, and transmitting an abort command to a control unit in communication with the channel subsystem in response to receiving the request to terminate the I/O operation. The method also includes transmitting a purge path command to purge a path associated with the I/O operation, where the purge path command includes an error code identifying the request to terminate the I/O operation.

Claims

1. A computer program product for handling early termination of an input/output (I/O) operation at a channel subsystem in an I/O processing system, the computer program product comprising:

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

receiving a request to terminate an I/O operation;

transmitting an abort command to a control unit in communication with the channel subsystem in response to receiving the request to terminate the I/O operation; and

transmitting a purge path command to purge a path associated with the I/O operation, wherein the purge path command includes an error code identifying the request to terminate the I/O operation.

2. The computer program product of claim 1 wherein the request to terminate the I/O operation is a clear subchannel command.

3. The computer program product of claim 2 wherein the abort command is transmitted in a first mode and the method further comprises:

switching communication protocols from the first mode to a second mode; and

transmitting a selective reset in a second mode.

4. The computer program product of claim 3 wherein the first mode is a transport mode supporting a transport control word (TCW) channel program and the second mode is a command mode supporting a channel command word (CCW) channel program.

5. The computer program product of claim 1 wherein the request to terminate the I/O operation is a halt subchannel command.

6. The computer program product of claim 1 wherein the request to terminate the I/O operation is a storage exception.

7. The computer program product of claim 1 wherein the method further comprises:

storing primary, secondary and alert status in response to transmitting the purge path command.

8. The computer program product of claim 1 wherein the abort command is transmitted on an open exchange and the purge path command is transmitted on a separate exchange.

9. An apparatus for handling early termination of an input/output (I/O) operation, the apparatus comprising:

a channel subsystem for communication with a control unit, the channel subsystem including one or more channels for directing information flow between memory and one or more I/O devices via the control unit, and performing a method comprising;

receiving a request to terminate an I/O operation;

transmitting an abort command to the control unit in response to receiving the request to terminate the I/O operation; and

transmitting a purge path command to purge a path associated with the I/O operation, wherein the purge path command includes an error code identifying the request to terminate the I/O operation.

10. The apparatus of claim 9 wherein the request to terminate the I/O operation is a clear subchannel command.

11. The apparatus of claim 10 wherein the abort command is transmitted in a first mode and the method performed by the channel subsystem further comprises:

switching communication protocols from the first mode to a second mode; and

transmitting a selective reset in a second mode.

12. The apparatus of claim 11 wherein the first mode is a transport mode supporting a transport control word (TCW) channel program and the second mode is a command mode supporting a channel command word (CCW) channel program.

13. The apparatus of claim 9 wherein the request to terminate the I/O operation is a halt subchannel command.

14. The apparatus of claim 9 wherein the request to terminate the I/O operation is a storage exception.

15. The apparatus of claim 9 wherein the method performed by the channel subsystem further comprises:

storing primary, secondary and alert status in response to transmitting the purge path command.

16. The apparatus of claim 9 wherein the abort command is transmitted on an open exchange and the purge path command is transmitted on a separate exchange.

17. A method for handling early termination of an input/output (I/O) operation at a channel subsystem in an I/O processing system, the method comprising:

receiving a request to terminate an I/O operation;

transmitting an abort command to a control unit in communication with the channel subsystem in response to receiving the request to terminate the I/O operation; and

transmitting a purge path command to purge a path associated with the I/O operation, wherein the purge path command includes an error code identifying the request to terminate the I/O operation.

18. The method of claim 17 wherein the request to terminate the I/O operation is a clear subchannel command.

19. The method of claim 18 wherein the abort command is transmitted in a first mode and the method further comprises:

switching communication protocols from the first mode to a second mode; and

transmitting a selective reset in a second mode.

20. The method of claim 19 wherein the first mode is a transport mode supporting a transport control word (TCW) channel program and the second mode is a command mode supporting a channel command word (CCW) channel program.

21. The method of claim 17 wherein the request to terminate the I/O operation is a halt subchannel command.

22. The method of claim 17 wherein the request to terminate the I/O operation is a storage exception.

23. The method of claim 17 further comprising:

storing primary, secondary and alert status in response to transmitting the purge path command.

24. The method of claim 17 wherein the abort command is transmitted on an open exchange and the purge path command is transmitted on a separate exchange.