Method of and system for managing reselection on a SCSI bus
AssigneeInternational Business Machines Corporation
InventorsBrian Lee Morger, Louise Ann Marier
Life of this patent
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Abstract
In a method of and a system for managing reselection of an initiator by a target on a SCSI bus, the target attempts to secure control of the bus for a first reselection cycle to reselect the initiator. If the target fails to secure control of the bus for the first reselection cycle and the target is selected by the initiator for a selection cycle, the target processes the selection cycle. However, concurrently with processing the selection cycle, substantially immediately after the bus becomes free, and before the target completes processing the selection cycle, the target attempts to secure control of the bus for a second reselection cycle to reselect the initiator.
Claims20
A method of managing reselection of an initiator by a target on a SCSI bus, which comprises the steps of:
- starting an arbitration phase of a first reselection cycle to reselect said initiator;
- whenever said target losses said first arbitration phase of said first reselection cycle and said target is selected by said initiator:
- waiting for a selection cycle to complete and said SCSI bus to become free;
- substantially immediately after said SCSI bus has become free, starting an arbitration phase of a second reselection cycle to reselect said initiator;
- if said target wins said arbitration phase of said second reselection cycle, pausing said second reselection cycle until said target at least partially processes said selection cycle and then completing said second reselection cycle.
A method of managing reselection of an initiator by a target on a SCSI bus, which comprises the steps of:
- attempting to secure control of said SCSI bus for a first reselection cycle to reselect said initiator;
- if said target fails to secure control of said SCSI bus for said first reselection cycle and said target is selected by said initiator for a selection cycle, substantially immediately after said SCSI bus becomes free at the completion of said selection cycle attempting to secure control of said bus for a second reselection cycle to reselect said initiator while said target completes processing of said selection cycle.
A method of managing reselection of an initiator by a target on a SCSI bus, which comprises the steps of:
- attempting to secure control of said SCSI bus for a first reselection cycle to reselect said initiator;
- if said target fails to secure control of said SCSI bus for said first reselection cycle and said target is selected by said initiator for a selection cycle, processing said selection cycle;
- and,
- substantially immediately after said SCSI bus becomes free at the completion of said selection cycle, and before said target completes processing said selection cycle, attempting to secure control of said SCSI bus for a second reselection cycle to reselect said initiator.
A target system for managing reselection of an initiator on a SCSI bus, said target system comprising:
- an interface controller coupled to said SCSI bus, said interface hardware including a reselection state machine;
- a programmable sequencer operatively connected to said interface controller, said programmable sequencer being programmed to start said reselection state machine substantially immediately after said SCSI bus becomes free if said target is selected by said initiator and a reselection start indicator is set;
- an interface processor operatively connected to said programmable sequencer, said interface processor being programmed to set said reselection start indicator at the start of a reselection cycle to reselect-said initiator.
Dependencies are inferred from the claim text.