LUN Portion Reassignment for Cache Consistency During Host Migration

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Solution Overview

Problem

Cache memory systems face challenges in efficiently managing migration events of applications between hosts, leading to inconsistencies and performance issues due to shared control of logical units (LUNs) and inadequate data access management.

Innovation Solution

The system compartmentalizes LUNs into portions assigned to specific hosts, detects migration events, and reassigns identified portions to the new host, updating ownership tracking structures and notifying the original host with cache invalidate requests to maintain data integrity and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If LUNs are shared between multiple hosts for flexible resource allocation, then adaptability is improved, but data access conflicts and performance issues occur during migration events

Engineering Contradiction:

Improvehost flexibilityVSAvoiddata access consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The LUN is divided into multiple portions with each portion assigned to a specific host. This segmentation allows the system to maintain flexible host allocation while ensuring data access consistency by giving each host exclusive access to its assigned portions, eliminating conflicts during migration events.

Inventive Principle:

Principle #1Segmentation

2Productivity

If cache memory is used to improve data access speed, then productivity is improved, but cache inconsistencies occur during application migration

Engineering Contradiction:

Improvedata access speedVSAvoidcache data consistency

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The system implements a feedback mechanism where the storage system notifies hosts of migration events and provides cache invalidate requests. This feedback loop ensures that cache memory maintains high performance by clearing inconsistent cache entries when migrations occur, preventing data consistency issues while preserving speed benefits.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If application migration between hosts is enabled for system maintenance, then ease of operation is improved, but data ownership conflicts arise

Engineering Contradiction:

Improveapplication mobilityVSAvoidownership management

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The system performs preliminary actions by pre-dividing the LUN into portions and assigning each to a specific host before migration events occur. This preliminary organization simplifies the migration process by clearly defining ownership boundaries in advance, reducing the complexity of managing data ownership during application mobility operations.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8909886B1System and method for improving cache performance upon detecting a migration event

Publication Date: 2014.12.09 EMC IP HLDG CO LLC

AI summary

A method, computer program product, and computing system for compartmentalizing a LUN into a plurality of portions that are each assigned to one or more hosts. The occurrence of a migration event in which an application being executed on a first host is being migrated to second host may be detected. Any portions within the LUN that are assigned to the application being executed on the first host may be identified, thus generating one or more identified portions. The one or more identified portions may be reassigned to the second host.