PROCESSING COMMUNICATION DATA IN A SHIPS PASSING CONDITION

• US 20090210562A1
• 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: Rcci, Louis W., Kalos, Matthew J., Huang, Catherine C., Flanagan, John R., Hathorn, Roger G., Casper, Daniel F.
• Granted Patent: US 9,052,837 B2
• Time in Patent Office: Days
• US Class Current: 710/5
• CPC Class Codes: G06F 13/28 using burst mode transfer, e.g. direct memory access DMA, cycle steal G06F13/32 takes precedence
• CPC Class Codes: G06F 13/4027 using bus bridges G06F13/4022 takes precedence
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0661 Format or protocol conversion arrangements
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

Articles of manufacture, apparatuses, and methods for processing communications between a control unit and a channel subsystem in an input/output processing system are disclosed. Embodiments of the invention include an article of manufacture including at least one computer usable medium having computer readable program code logic to processing communications between a control unit and a channel subsystem in an input/output processing system. The computer readable program code logic performs a method including: sending a message in a first mode from the control unit to the channel subsystem; receiving a command in a second mode from the channel subsystem at the control unit; determining whether the command is responsive to the message; and responsive to the command being not responsive to the message, determining whether to perform one of i) executing the command and ii) terminating the command.

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 a message in a first mode from the control unit to the channel subsystem;

receiving a command in a second mode from the channel subsystem at the control unit;

determining whether the command is responsive to the message; and

responsive to the command being not responsive to the message, determining whether to perform one of i) executing the command and ii) terminating the command.

2. The computer program product of claim 1, wherein the first mode uses a first protocol including Channel Command Words (CCW), and the second mode uses a second protocol including Transport Control Words (TCW).

3. The computer program product of claim 1, further comprising at least one of i) receiving the command on a first exchange, ii) sending the message on a second exchange, and iii) awaiting a response message from the channel subsystem on a third exchange.

4. The computer program product of claim 3, wherein the message is an asynchronous device status, and the response message is a stack status message.

5. The computer program product of claim 3, wherein determining is responsive to the response message received from the channel subsystem.

6. The computer program product claim 3, further comprising:

setting a time period for receipt of the response message, and

responsive to expiration of the time period without receiving the response message, aborting the first exchange and the second exchange.

7. The computer program product of claim 1, further comprising sending a response message in response to the command, the response message comprising at least one of an indication of execution of the command and a device status.

8. The computer program product of claim 1, wherein:

sending the message comprises opening a first exchange and sending a status message in a first mode on the first exchange and setting a time period for receipt of a response message from the channel subsystem in response to the status message, the first mode using a first protocol that includes Channel Command Words (CCW);

receiving the command comprises receiving the command in a second mode on a second exchange, the second mode using a second protocol including Transport Control Words (TCW); and

determining whether to perform comprises;

awaiting a response message from the channel subsystem in the first mode on a third exchange; and

responsive to the response message, determining whether to perform one of i) executing the command and ii) terminating the command, and sending a response message in the second mode on the second exchange in response to the command, the response message comprising at least one of;

an indication of execution of the command, and a device status.

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

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

sending a message in a first mode to the channel subsystem;

receiving a command in a second mode from the channel subsystem;

determining whether the command is responsive to the message; and

responsive to the command being not responsive to the message, determining whether to perform one of i) executing the command and ii) terminating the command.

10. The apparatus of claim 9, wherein the first mode uses a first protocol including Channel Command Words (CCW), and the second mode uses a second protocol including Transport Control Words (TCW).

11. The apparatus of claim 9, further comprising at least one of i) receiving the command on a first exchange, ii) sending the message on a second exchange, and iii) awaiting a response message from the channel subsystem on a third exchange.

12. The apparatus of claim 11, wherein the message is an asynchronous device status, and the response message is a stack status message.

13. The apparatus of claim 11, wherein determining is responsive to the response message received from the channel subsystem.

14. The apparatus claim 11, further comprising:

setting a time period for receipt of the response message, and

responsive to expiration of the time period without receiving the response message, aborting the first exchange and the second exchange.

15. The apparatus of claim 9, wherein:

sending the message comprises opening a first exchange and sending a status message in a first mode on the first exchange and setting a time period for receipt of a response message from the channel subsystem in response to the status message, the first mode using a first protocol that includes Channel Command Words (CCW);

receiving the command comprises receiving the command in a second mode on a second exchange, the second mode using a second protocol including Transport Control Words (TCW); and

determining whether to perform comprises;

awaiting a response message from the channel subsystem in the first mode on a third exchange; and

responsive to the response message, determining whether to perform one of i) executing the command and ii) terminating the command, and sending a response message in the second mode on the second exchange in response to the command, the response message comprising at least one of;

an indication of execution of the command, and a device status.

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

sending a message from the control unit to the channel subsystem;

receiving a command from the channel subsystem at the control unit;

determining whether the command is responsive to the message; and

responsive to the command being not responsive to the message, determining whether to perform one of i) executing the command and ii) terminating the command.

17. The method of claim 16, wherein the first mode uses a first protocol including Channel Command Words (CCW), and the second mode uses a second protocol including Transport Control Words (TCW).

18. The method of claim 16, further comprising at least one of i) receiving the command on a first exchange, ii) sending the message on a second exchange, and iii) awaiting a response message from the channel subsystem on a third exchange.

19. The method of claim 18, wherein the message is an asynchronous device status, and the response message is a stack status message.

20. The method of claim 16, wherein:

sending the message comprises opening a first exchange and sending a status message in a first mode on the first exchange and setting a time period for receipt of a response message from the channel subsystem in response to the status message, the first mode using a first protocol that includes Channel Command Words (CCW);

receiving the command comprises receiving the command in a second mode on a second exchange, the second mode using a second protocol including Transport Control Words (TCW); and

determining whether to perform comprises;

awaiting a response message from the channel subsystem in the first mode on a third exchange; and

responsive to the response message, determining whether to perform one of i) executing the command and ii) terminating the command, and sending a response message in the second mode on the second exchange in response to the command, the response message comprising at least one of;

an indication of execution of the command, and a device status.