Method and apparatus using attached hardware subsystem to communicate between attached hosts

• US 20030236910A1
• Filed: 05/28/2002
• Published: 12/25/2003
• Est. Priority Date: 05/28/2002
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Micka, William Frank, Perry, Larry Richard, Slone, Harold Glen
• Granted Patent: US 7,480,697 B2
• Time in Patent Office: Days
• US Class Current: 709/234
• CPC Class Codes: G06F 13/385 for adaptation of a particular data processing system to different peripheral devices

Abstract

A method for sending a message from one host (16) to at least one other host, both of which are attached to a hardware subsystem (12) that is bidirectionally coupled to a mass data storage unit (14) includes (a) transferring a Send Message command through a channel (18) from a first attached host to the hardware subsystem, the Send Message command having at least one second attached host as an intended recipient; (b) buffering (20) at least a message payload portion of the Send Message command at the hardware subsystem and generating an unsolicited interrupt in the at least one second attached host; and (c) in response to the unsolicited interrupt, transferring a Request Message command through a channel from the at least one second attached host to the hardware subsystem for obtaining at least the message payload portion buffered at the hardware subsystem. The Send Message command may be a point-to-point message having a single other attached host as an intended recipient, or it may be a point-to-multipoint message having a plurality of other attached hosts as intended recipients. The hardware subsystem need have no knowledge of the message contents sent between hosts.

Claims

1. A method for sending a message from one host to at least one other host both of which are attached to a hardware subsystem that is bidirectionally coupled to a mass data storage unit, comprising:

transferring a message origination command through a channel from a first attached host to the hardware subsystem, the message origination command having at least one second attached host as an intended recipient;

buffering at least a message payload portion of the message origination command at the hardware subsystem and generating an interrupt in the at least one second attached host; and

in response to the generated interrupt, transferring a message retrieval command through a channel from the at least one second attached host to the hardware subsystem for retrieving at least the message payload portion buffered at the hardware subsystem.

2. A method as in claim 1, where the message origination command comprises a point-to-point message having a single other attached host as an intended recipient.

3. A method as in claim 1, where the message origination command comprises a point-to-multipoint message having a plurality of other attached hosts as intended recipients.

4. A method as in claim 1, where the message origination command comprises a channel input/output command that is addressed to a single other attached host.

5. A method as in claim 1, where the message origination command comprises a channel input/output command that is addressed to a plurality of other attached hosts.

6. A method as in claim 1, where the message origination command comprises a channel input/output command that is addressed to all other attached hosts.

7. A method as in claim 1, where the mass data storage unit comprises at least one disk that is used by each of the attached hosts.

8. A method as in claim 1, where the mass data storage unit comprises at least one disk, and where the message origination command is sent when changing shared information that is stored on the at least one disk.

9. A method as in claim 1, where the interrupt comprises an unsolicited interrupt.

10. A data processing system comprising a hardware subsystem and a plurality of hosts that are bidirectionally coupled to said hardware subsystem through respective host adapters and channels, said hardware subsystem being bidirectionally coupled to a mass data storage unit that is shared by said plurality of hosts, comprising stored programs in said hardware subsystem and in each of said plurality of hosts for causing a data processor in a first attached host to transfer a message origination command through an associated channel from said first attached host to said hardware subsystem, the message origination command having at least one second attached host as an intended recipient;

said hardware subsystem comprising a message buffer for buffering at least a message payload portion of the message origination command received through said channel and a data processor executing a stored program for interrupting the at least one second attached host, said at least one second attached host comprising a data processor executing a stored program for causing, in response to the interrupt, the transfer of a retrieve message command through a channel from the at least one second attached host to the hardware subsystem for obtaining at least the message payload portion from said message buffer.

11. A system as in claim 10, where the message origination command comprises a point-to-point message having a single other attached host as an intended recipient.

12. A system as in claim 10, where the message origination command comprises a point-to-multipoint message having a plurality of other attached hosts as intended recipients.

13. A system as in claim 10, where the message origination command comprises a channel input/output command that is addressed to a single other attached host.

14. A system as in claim 10, where the message origination command comprises a channel input/output command that is addressed to a plurality of other attached hosts.

15. A system as in claim 10, where the message origination command comprises a channel input/output command that is addressed to all other attached hosts.

16. A system as in claim 10, where the mass data storage unit comprises at least one disk that is shared by each of the attached hosts.

17. A system as in claim 16, where message origination command is sent in conjunction with changing shared information that is stored on the at least one disk.

18. A system as in claim 10, where the interrupt comprises an unsolicited interrupt.

19. A storage area network comprising a hardware subsystem, a plurality of hosts and a plurality of host adapters and channels, individual ones of said plurality of hosts being bidirectionally coupled to said hardware subsystem through a respective host adapter and a channel, said hardware subsystem being bidirectionally coupled to a mass data storage unit that is shared by said plurality of hosts, an attached host comprising messaging means for transmitting a message origination command through the associated channel to said hardware subsystem, the message origination command specifying at least one other attached host as an intended recipient for a message payload portion of the message origination command;

said hardware subsystem comprising buffer means for buffering at least the message payload portion of the message origination command received through said channel and further comprising means for interrupting the specified recipient host, said specified recipient host comprising means, responsive to the interrupt, for transmitting a retrieve message command through the associated channel for retrieving from said buffer means at least the buffered message payload portion.

20. A system as in claim 19, where the message origination command comprises a point-to-point message having a single other attached host as an intended recipient.

21. A system as in claim 19, where the message origination command comprises a point-to-multipoint message having a plurality of other attached hosts as intended recipients.

22. A system as in claim 19, where the message origination command comprises a channel input/output command that is addressed to a single other attached host.

23. A system as in claim 19, where the message origination command comprises a channel input/output command that is addressed to a plurality of other attached hosts.

24. A system as in claim 19, where the message origination command comprises a channel input/output command that is addressed to all other attached hosts.

25. A hardware subsystem comprising a plurality of host adapter means for bidirectionally coupling to a plurality of hosts through channels, said hardware subsystem being bidirectionally coupled to a mass data storage unit that is shared by said plurality of hosts, said hardware subsystem comprising message reception means for receiving a message origination command sent by an attached host through the associated channel, the message origination command specifying at least one other attached host as an intended recipient for a message payload portion of the message origination command;

said hardware subsystem further comprising buffer means for buffering at least the message payload portion of the message origination command received through said channel;

means for interrupting the specified recipient host and message response means, responsive to a retrieve message command received through the associated channel from the interrupted specified host, for retrieving from said buffer means at least the buffered message payload portion and for transmitting at least the retrieved buffered message payload portion to the interrupted specified host.

26. A hardware subsystem as in claim 25, where the message origination command comprises a point-to-point message having a single other attached host as an intended recipient.

27. A hardware subsystem as in claim 25, where the message origination command comprises a point-to-multipoint message having a plurality of other attached hosts as intended recipients.

28. A hardware subsystem as in claim 25, where the message origination command comprises a channel input/output command that is addressed to a single other attached host.

29. A hardware subsystem as in claim 25, where the message origination command comprises a channel input/output command that is addressed to a plurality of other attached hosts.

30. A hardware subsystem as in claim 25, where the message origination command comprises a channel input/output command that is addressed to all other attached hosts.

31. A host for coupling through a channel and a channel adapter means to a hardware subsystem that is bidirectionally coupled to a mass data storage unit that is shared by a plurality of hosts, said host comprising message transmission means for transmitting a message origination command through the channel to the hardware subsystem, the message origination command specifying at least one other attached host as an intended recipient for a message payload portion of he message origination command;

said host further comprising message reception means operable in response to an interrupt generated by said hardware subsystem for transmitting a retrieve message command through the channel to the hardware subsystem for causing the hardware subsystem to retrieve at least a buffered message payload portion that was sent by another host in a message origination command.

32. A host as in claim 31, where the message origination command comprises a point-to-point message having a single other attached host as an intended recipient.

33. A host as in claim 31, where the message origination command comprises a point-to-multipoint message having a plurality of other attached hosts as intended recipients.

34. A host as in claim 31, where the message origination command comprises a channel input/output command that is addressed to a single other attached host.

35. A host as in claim 31, where the message origination command comprises a channel input/output command that is addressed to a plurality of other attached hosts.

36. A host as in claim 31, where the message origination command comprises a channel input/output command that is addressed to all other attached hosts.

37. A method for modifying a volume table of contents VTOC in amass data storage unit of a data processing system that comprises a hardware subsystem and a plurality of hosts that are bidirectionally coupled to the hardware subsystem through respective channels, said hardware subsystem being bidirectionally coupled to said mass data storage unit that is shared by said plurality of hosts, comprising:

transferring a message origination command through a channel from a first attached host to the hardware subsystem, the message origination command having at least one second attached host as an intended recipient and comprising a notification of a modification to a VTOC;

buffering at least a portion of the message origination command at the hardware subsystem and generating an interrupt in the at least one second attached host; and

in response to the generated interrupt, transferring a message retrieval command through a channel from the at least one second attached host to the hardware subsystem for retrieving the buffered message from the hardware subsystem and receiving the notification of the modification to the VTOC.

38. A method for sending a message from one host to a plurality of other hosts, all of which are attached to a hardware subsystem that is bidirectionally coupled to a mass data storage unit, comprising:

transferring a message origination command through a channel from a first attached host to the hardware subsystem, the message origination command specifying the plurality of other hosts as an intended recipients;

buffering at least a message payload portion of the message origination command at the hardware subsystem and generating an interrupt in each of the specified ones of the plurality of other hosts; and

in response to the generated interrupt, transferring a message retrieval command from individual ones of the plurality of other hosts for retrieving at least the message payload portion buffered at the hardware subsystem.

39. A method for modifying shared data stored on a mass data storage unit of a data processing system that comprises a hardware subsystem and a plurality of hosts that are each bidirectionally coupled to the hardware subsystem, said hardware subsystem being bidirectionally coupled to said mass data storage unit, comprising:

transferring a point-to-multipoint message origination input/output command from a first attached host to the hardware subsystem, the message origination command specifying a plurality of other attached hosts as intended recipients and comprising a notification of a modification made to shared data stored on said mass data storage unit;

buffering at least a portion of the message origination command at the hardware subsystem and generating an interrupt in all of the specified intended recipient hosts; and

in response to the generated interrupt, sending a message retrieval input/output command from each of the specified intended recipient hosts to the hardware subsystem for retrieving the buffered message from the hardware subsystem and thereby receiving the notification of the modification to the shared data.

40. A method as in claim 39, where the shared data comprises a disk volume table of contents.