PERSISTENT INFORMATION UNIT PACING

• US 20080059638A1
• Filed: 08/30/2006
• Published: 03/06/2008
• Est. Priority Date: 08/30/2006
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Huang, Catherine C., Hathorn, Roger Gregory, Casper, Daniel Francis, Flanagan, John
• Granted Patent: US 8,032,581 B2
• Time in Patent Office: Days
• US Class Current: 709/227
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/33 using forward notification
• CPC Class Codes: H04L 47/35 by embedding flow control information in regular packets, e.g. piggybacking

Abstract

Provided are a method, system, and article of manufacture, wherein a control unit receives a request to establish a relationship over a fibre channel connection, wherein a first indicator associated with the request indicates that the relationship supports persistent information unit pacing across a plurality of command chains. The control unit sends a response indicating an acceptance of the relationship, wherein a second indicator associated with the response indicates that the control unit supports persistent information unit pacing across the plurality of command chains. An information unit pacing parameter value is retained across the plurality of command chains, in response to determining that the second indicator indicates that the control unit supports persistent information unit pacing across the plurality of command chains.

Claims

1. A method, comprising:

receiving, at a control unit, a request to establish a relationship over a fibre channel connection, wherein a first indicator associated with the request indicates that the relationship supports persistent information unit pacing across a plurality of command chains;

sending, by the control unit, a response indicating an acceptance of the relationship, wherein a second indicator associated with the response indicates that the control unit supports persistent information unit pacing across the plurality of command chains; and

retaining an information unit pacing parameter value across the plurality of command chains, in response to determining that the second indicator indicates that the control unit supports persistent information unit pacing across the plurality of command chains.

2. The method of claim 1, wherein the relationship is a logical path, wherein the request comprises an establish logical path function in a fibre channel protocol, wherein the response is a logical path established response in the fibre channel protocol, wherein parameters of the establish logical path function and the logical path established response include the first and the second indicators, and wherein the first and the second indicators are bits.

3. The method of claim 1, wherein a command chain comprises a sequence of commands, wherein the information unit pacing parameter value is set to a number that is different from a default value of sixteen, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight at any time across the plurality of command chains, the method further comprising:

starting a first sequence of commands, wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the first sequence of commands;

starting a second sequence of commands in response to a completion of the processing of the first sequence of commands, wherein the information unit pacing parameter value remains unchanged, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the second sequence of commands.

4. The method of claim 1, wherein the first indicator and the second indicator are included as an enhancement to a fibre channel protocol, wherein the enhancement to the fibre channel protocol supports persistent information unit pacing across the plurality of command chains.

5. The method of claim 1, wherein the control unit is included in a storage controller, wherein the request is received from a remote host coupled to the storage controller, wherein the information unit pacing parameter value is retained either on a logical path basis or on a physical path basis, and wherein the information unit pacing parameter value is capable of being reset to a default value.

6. A system, comprising:

a control unit;

a fibre channel connection for communication with the control unit;

a processor in communication with the control unit; and

memory coupled to the processor, wherein the processor performs operations, the operations comprising;

(i) receiving, at the control unit, a request to establish a relationship over the fibre channel connection, wherein a first indicator associated with the request indicates that the relationship supports persistent information unit pacing across a plurality of command chains;

(ii) sending, by the control unit, a response indicating an acceptance of the relationship, wherein a second indicator associated with the response indicates that the control unit supports persistent information unit pacing across the plurality of command chains; and

(iii) retaining an information unit pacing parameter value across the plurality of command chains, in response to determining that the second indicator indicates that the control unit supports persistent information unit pacing across the plurality of command chains.

7. The system of claim 6, wherein the relationship is a logical path, wherein the request comprises an establish logical path function in a fibre channel protocol, wherein the response is a logical path established response in the fibre channel protocol, wherein parameters of the establish logical path function and the logical path established response include the first and the second indicators, and wherein the first and the second indicators are bits.

8. The system of claim 6, wherein a command chain comprises a sequence of commands, wherein the information unit pacing parameter value is set to a number that is different from a default value of sixteen, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight at any time across the plurality of command chains, the operations further comprising:

starting a first sequence of commands, wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the first sequence of commands;

starting a second sequence of commands in response to a completion of the processing of the first sequence of commands, wherein the information unit pacing parameter value remains unchanged, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the second sequence of commands.

9. The system of claim 6, wherein the first indicator and the second indicator are included as an enhancement to a fibre channel protocol, wherein the enhancement to the fibre channel protocol supports persistent information unit pacing across the plurality of command chains.

10. The system of claim 6, wherein the control unit is included in a storage controller, wherein the request is received from a remote host coupled to the storage controller, wherein the information unit pacing parameter value is retained either on a logical path basis or on a physical path basis, and wherein the information unit pacing parameter value is capable of being reset to a default value.

11. An article of manufacture, wherein the article of manufacture is capable of causing operations in a machine, the operations comprising:

receiving, at a control unit, a request to establish a relationship over a fibre channel connection, wherein a first indicator associated with the request indicates that the relationship supports persistent information unit pacing across a plurality of command chains;

sending, by the control unit, a response indicating an acceptance of the relationship, wherein a second indicator associated with the response indicates that the control unit supports persistent information unit pacing across the plurality of command chains; and

retaining an information unit pacing parameter value across the plurality of command chains, in response to determining that the second indicator indicates that the control unit supports persistent information unit pacing across the plurality of command chains.

12. The article of manufacture of claim 11, wherein the relationship is a logical path, wherein the request comprises an establish logical path function in a fibre channel protocol, wherein the response is a logical path established response in the fibre channel protocol, wherein parameters of the establish logical path function and the logical path established response include the first and the second indicators, and wherein the first and the second indicators are bits.

13. The article of manufacture of claim 11, wherein a command chain comprises a sequence of commands, wherein the information unit pacing parameter value is set to a number that is different from a default value of sixteen, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight at any time across the plurality of command chains, the operations further comprising:

starting a first sequence of commands, wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the first sequence of commands;

starting a second sequence of commands in response to a completion of the processing of the first sequence of commands, wherein the information unit pacing parameter value remains unchanged, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the second sequence of commands.

14. The article of manufacture of claim 11, wherein the first indicator and the second indicator are included as an enhancement to a fibre channel protocol, wherein the enhancement to the fibre channel protocol supports persistent information unit pacing across the plurality of command chains.

15. The article of manufacture of claim 11, wherein the control unit is included in a storage controller, wherein the request is received from a remote host coupled to the storage controller, wherein the information unit pacing parameter value is retained either on a logical path basis or on a physical path basis, and wherein the information unit pacing parameter value is capable of being reset to a default value.

16. A method for deploying computing infrastructure, comprising integrating computer-readable code into a storage controller and a remote host, wherein the code in combination with the storage controller and the remote host is capable of performing:

receiving, at a control unit, a request to establish a relationship over a fibre channel connection, wherein a first indicator associated with the request indicates that the relationship supports persistent information unit pacing across a plurality of command chains;

sending, by the control unit, a response indicating an acceptance of the relationship, wherein a second indicator associated with the response indicates that the control unit supports persistent information unit pacing across the plurality of command chains; and

retaining an information unit pacing parameter value across the plurality of command chains, in response to determining that the second indicator indicates that the control unit supports persistent information unit pacing across the plurality of command chains.

17. The method for deploying computing infrastructure of claim 16, wherein the relationship is a logical path, wherein the request comprises an establish logical path function in a fibre channel protocol, wherein the response is a logical path established response in the fibre channel protocol, wherein parameters of the establish logical path function and the logical path established response include the first and the second indicators, and wherein the first and the second indicators are bits.

18. The method for deploying computing infrastructure of claim 16, wherein a command chain comprises a sequence of commands, wherein the information unit pacing parameter value is set to a number that is different from a default value of sixteen, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight at any time across the plurality of command chains, the method further comprising:

starting a first sequence of commands, wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the first sequence of commands;

starting a second sequence of commands in response to a completion of the processing of the first sequence of commands, wherein the information unit pacing parameter value remains unchanged, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the second sequence of commands.

19. The method for deploying computing infrastructure of claim 16, wherein the first indicator and the second indicator are included as an enhancement to a fibre channel protocol, wherein the enhancement to the fibre channel protocol supports persistent information unit pacing across the plurality of command chains.

20. The method for deploying computing infrastructure of claim 16, wherein the control unit is included in the storage controller, wherein the request is received from the remote host, wherein the remote host is coupled to the storage controller, wherein the information unit pacing parameter value is retained either on a logical path basis or on a physical path basis, and wherein the information unit pacing parameter value is capable of being reset to a default value.

21. A system, comprising:

a control unit;

a fibre channel connection for communication with the control unit;

means for receiving, at the control unit, a request to establish a relationship over the fibre channel connection, wherein a first indicator associated with the request indicates that the relationship supports persistent information unit pacing across a plurality of command chains;

means for sending, by the control unit, a response indicating an acceptance of the relationship, wherein a second indicator associated with the response indicates that the control unit supports persistent information unit pacing across the plurality of command chains; and

means for retaining an information unit pacing parameter value across the plurality of command chains, in response to determining that the second indicator indicates that the control unit supports persistent information unit pacing across the plurality of command chains.

22. The system of claim 21, wherein the relationship is a logical path, wherein the request comprises an establish logical path function in a fibre channel protocol, wherein the response is a logical path established response in the fibre channel protocol, wherein parameters of the establish logical path function and the logical path established response include the first and the second indicators, and wherein the first and the second indicators are bits.

23. The system of claim 21, wherein a command chain comprises a sequence of commands, wherein the information unit pacing parameter value is set to a number that is different from a default value of sixteen, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight at any time across the plurality of command chains, the system further comprising:

means for starting a first sequence of commands, wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the first sequence of commands;

means for starting a second sequence of commands in response to a completion of the processing of the first sequence of commands, wherein the information unit pacing parameter value remains unchanged, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the second sequence of commands.

24. The system of claim 21, wherein the first indicator and the second indicator are included as an enhancement to a fibre channel protocol, wherein the enhancement to the fibre channel protocol supports persistent information unit pacing across the plurality of command chains.

25. The system of claim 21, wherein the control unit is included in a storage controller, wherein the request is received from a remote host coupled to the storage controller, wherein the information unit pacing parameter value is retained either on a logical path basis or on a physical path basis, and wherein the information unit pacing parameter value is capable of being reset to a default value.

26. A computer readable medium, wherein the computer readable medium includes machine readable instructions stored thereon, wherein the machine readable instructions cause operations on a computer, the operations comprising:

receiving, at a control unit, a request to establish a relationship over a fibre channel connection, wherein a first indicator associated with the request indicates that the relationship supports persistent information unit pacing across a plurality of command chains;

sending, by the control unit, a response indicating an acceptance of the relationship, wherein a second indicator associated with the response indicates that the control unit supports persistent information unit pacing across the plurality of command chains; and

retaining an information unit pacing parameter value across the plurality of command chains, in response to determining that the second indicator indicates that the control unit supports persistent information unit pacing across the plurality of command chains.

27. The computer readable medium of claim 26, wherein the relationship is a logical path, wherein the request comprises an establish logical path function in a fibre channel protocol, wherein the response is a logical path established response in the fibre channel protocol, wherein parameters of the establish logical path function and the logical path established response include the first and the second indicators, and wherein the first and the second indicators are bits.

28. The computer readable medium of claim 26, wherein a command chain comprises a sequence of commands, wherein the information unit pacing parameter value is set to a number that is different from a default value of sixteen, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight at any time across the plurality of command chains, the operations further comprising:

starting a first sequence of commands, wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the first sequence of commands;

starting a second sequence of commands in response to a completion of the processing of the first sequence of commands, wherein the information unit pacing parameter value remains unchanged, and wherein the information unit pacing parameter value indicates the number of information units that can be in flight across the fibre channel connection during a processing of the second sequence of commands.

29. The computer readable medium of claim 26, wherein the first indicator and the second indicator are included as an enhancement to a fibre channel protocol, wherein the enhancement to the fibre channel protocol supports persistent information unit pacing across the plurality of command chains.

30. The computer readable medium of claim 26, wherein the control unit is included in a storage controller, wherein the request is received from a remote host coupled to the storage controller, wherein the information unit pacing parameter value is retained either on a logical path basis or on a physical path basis, and wherein the information unit pacing parameter value is capable of being reset to a default value.