FCP Write Command Data Matching via Identifier

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Solution Overview

Problem

Fibre Channel Protocol (FCP) data exchanges between an initiator and a receiver often result in data integrity errors due to incorrect association with write commands, leading to resource consumption, complexity, and incompatibilities in existing solutions such as long timeouts and scanning of open exchanges.

Innovation Solution

A method is introduced where a unique identifier is added to the command descriptor block (CDB) and appended to the data frame, ensuring correct data association by verifying the identifier at the receiver before caching, thus preventing incorrect data matching and reducing disruptive impacts on other operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a long timeout value is implemented to ensure data is correctly associated with the appropriate write command, then data integrity is improved, but computing resources are tied up during the timeout period and system complexity increases

Engineering Contradiction:

Improvedata integrityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by including an identifier field in the write command that is used to match data frames before the timeout period expires. The identifier is placed in the command descriptor block (CDB) and referenced in data frame headers, allowing the receiver to correctly associate data with the appropriate command immediately upon receipt, rather than waiting for a timeout to confirm correctness.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a long timeout value is implemented to ensure data is correctly associated with the appropriate write command, then data integrity is improved, but computing resources are consumed during the timeout period

Engineering Contradiction:

Improvedata integrityVSAvoidcomputing resource consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The identifier matching mechanism performs the data association task immediately when data frames are received, using the identifier included in the write command. This eliminates the need for prolonged timeout periods where computing resources would be idle or engaged in resource-intensive scanning operations to verify data correctness.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If scanning of open exchanges is performed to ensure correct data association, then data integrity is improved, but device complexity and resource consumption increase

Engineering Contradiction:

Improvedata integrityVSAvoidsystem performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent extracts the essential matching information (identifier) from the write command and places it directly in the command descriptor block and data frame headers. This allows the receiver to perform simple identifier comparison rather than scanning through multiple open exchanges to determine which command the data belongs to, significantly reducing processing overhead and improving performance.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS7853726B2FCP command-data matching for write operations

Publication Date: 2010.12.14 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A method for performing a data exchange between an initiator and a receiver in a fiber channel protocol (FCP) is provided. A control flag is set in a write command to indicate the presence of an identifier. The identifier is copied into a command descriptor block (CDB) of the write command and appended to a data frame. The write command and data frame, including the identifier, is sent from the initiator to the receiver.