Claims
- 1. A SCSI semantics distribution system for linking a host to storage devices over a network, the system comprising:
an agent connected to the host, the agent storing a first copy of the SCSI semantics; and a controller coupled to the agent, the controller storing a second copy of the SCSI semantics, the controller intermittently causing contents of the first copy of the SCSI semantics to be replaced by contents of the second copy of the SCSI semantics, wherein during an input/output (I/O) operation between the host and the storage device, the agent accesses the first copy of the SCSI semantics as part of the I/O operation.
- 2. The system of claim 1, wherein the controller has non-volatile memory, whereby the second copy is stored in the non-volatile memory.
- 3. The system of claim 1, wherein the agent has volatile memory, whereby the first copy is stored in the volatile memory.
- 4. The system of claim 1, wherein the agent has volatile and non-volatile memory for storing the first copy.
- 5. The system of claim 1, wherein the first copy of the SCSI semantics includes a task state.
- 6. The system of claim 2, wherein the second copy of the SCSI semantics does not include the task state.
- 7. The system of claim 1, wherein the controller monitors changes in the SCSI semantics and updates the second copy of the SCSI semantics according to these changes.
- 8. The system of claim 7 wherein, the controller transfers changes in the second copy of the SCSI semantics to the first copy of the SCSI semantics.
- 9. The system of claim 1, wherein complex SCSI semantics are stored at second copy and not the first copy.
- 10. The system of claim 9, wherein the controller sends an intermittent status signal to the agent.
- 11. The system of claim 10, wherein the intermittent status signal is periodic.
- 12. The system of claim 10, wherein the SCSI semantics includes a Not-Ready state that, when active, prevents I/O operations between the storage device and the host and the agent activates the Not Ready state if the agent does not receive the status signal.
- 13. The system of claim 1 further comprising multiple agents, each having a different first copy of the SCSI semantics.
- 14. The system of claim 1, wherein the agent reports an error during an I/O operation to the controller.
- 15. The system of claim 14, wherein the controller responds to the error report.
- 16. The system of claim 1, wherein, the controller issues a command to the agent, the command altering the first copy of the SCSI semantics.
- 17. The system of claim 16, wherein after altering the first copy, the agent responds to the command.
- 18. The system of claim 1, wherein frequently accessed SCSI semantics are contained in the first copy.
- 19. The system of claim 1, wherein the SCSI semantics comprise vendor states.
- 20. The system of claim 19, wherein said vendor states are hardwired to the first copy.
- 21. The system of claim 19, wherein said vendor states are determined by the controller.
- 22. The system of claim 1, wherein the SCSI semantics comprise geometry states.
- 23. The system of claim 19, wherein said geometry states are hardwired to the first copy.
- 24. The system of claim 19, wherein said geometry states are determined by the controller.
- 25. A method for distributing SCSI semantics for a virtual drive, the method comprising the steps of:
storing a first copy of the SCSI semantics, whereby the first copy is accessed during I/O operations; storing a second copy at of the SCSI semantics whereby, some contents of the first copy are intermittently replaced by contents of the second copy.
- 26. The method of claim 25, whereby the first copy stores frequently accessed SCSI semantics.
- 27. The method of claim 25, whereby the first copy, and not the second copy, contain the task state.
- 28. The method of claim 25 further comprising the steps of intermittently sending a signal to an agent containing the first copy.
- 29. The method of claim 28 further comprising activating a non-ready state in the SCSI semantics in the first copy if the agent does not receive the signal.
RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional Application No. 60/208,971, filed on Jun. 2, 2000, the disclosure of which is hereby incorporated by reference in full.
Provisional Applications (1)
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Number |
Date |
Country |
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60208971 |
Jun 2000 |
US |