I/O Suspension Protocol for Logical Path Stability
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Solution Overview
Problem
Current link protocols lack the ability to exchange operating parameters between the channel and the control unit, leading to errors and potential loss of logical paths due to the reliance on busy messages for suspending commands.
Innovation Solution
A system and method that allows for the exchange of selected operating parameters and suspension of input/output operations between an initiator and a target in an input/output processing system, using messages to request suspension of operations for a defined period, enabling system changes such as updates or parameter changes without disrupting I/O operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current link protocols are used to suspend commands, then the control unit can respond to new commands with a busy message, but this may result in errors and possible loss of the logical path established between the control unit and the channel
Solution Approach 1:
The patent introduces a new link protocol that acts as an intermediary mechanism between the channel and control unit. This protocol provides a dedicated suspension request message that mediates the command suspension process, replacing the problematic busy message approach. The suspension request message serves as a formal intermediary signal that allows the control unit to pause command processing without disrupting the logical path establishment or causing errors.
2Ease of operation
If the channel ceases sending new commands or the control unit responds with busy messages, then command suspension is achieved, but this may result in errors and possible loss of the logical path
Solution Approach 1:
The patent changes the operational parameters of the link protocol by introducing a new message type (suspension request message) with specific parameters including a suspension indicator and an optional time period field. This parameter change transforms the interaction model from reactive busy messages to proactive suspension requests, allowing the channel to formally request suspension with controlled parameters rather than relying on error-prone busy message responses.
3Adaptability or versatility
If no link protocol allows exchange of operating parameters, then the system maintains simplicity, but the control unit cannot request suspension of commands for a selected time period
Solution Approach 1:
The patent applies preliminary action by establishing the new link protocol with suspension capability before it is needed. The protocol includes pre-defined message structures, suspension indicators, and time period parameters that are prepared in advance. This preliminary establishment of the communication framework allows the control unit to request suspension for selected time periods without requiring complex runtime negotiations or ad-hoc protocol extensions.
Data Source
AI summary
A computer program product, an apparatus, and a method for processing communications between a target and an initiator an input/output processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes: sending a message from the initiator to the target, the message requesting suspension of input/output operations between the initiator and the target for a period of time, the period of time being defined by the message; responsive to the message, suspending input/output operation messages for the period of time; performing a system change comprising at least one of: at least one update, a computer program installation, a recovery, and a change in operating parameters; and initiating new input/output operations after at least one of: expiration of the period of time and initiation of new input/output operations by the initiator.