Data Migration System Using Thin Provisioning

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Solution Overview

Problem

During data migration from a logical volume in a first storage system to a thin provisioning (TP) volume in a second storage system, invalid data is transferred, leading to inefficient use of storage capacity at the migration destination, as physical pages are assigned to virtual pages even if the data is invalid, resulting in increased storage capacity usage.

Innovation Solution

The data migration system employs a combination of external coupling through storage virtualization and internal copying, where only valid data is migrated, and invalid data is not assigned physical pages at the migration destination, using thin provisioning information to manage the migration process, allowing for efficient data transfer while receiving access requests from the host.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If data migration is performed from a logical volume to a thin provisioning volume using conventional methods, then data transfer is completed, but invalid data is also transferred and physical pages are assigned to virtual pages even when the data is invalid, resulting in inefficient storage capacity utilization

Engineering Contradiction:

Improvestorage capacity utilizationVSAvoidwasted storage capacity

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

The patent extracts and identifies valid data from invalid data during the migration process. By examining thin provisioning information from the source storage system, the system determines which virtual pages contain valid data and extracts only those portions for migration, leaving invalid data behind in the source system.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary analysis of thin provisioning information before actual data migration begins. The system预先 determines which virtual pages contain valid data by checking the source storage system's thin provisioning metadata, allowing it to plan the migration to only include necessary data portions.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If all data from the source volume is migrated to the destination TP volume, then complete data transfer is achieved, but the total amount of migration target data increases unnecessarily due to inclusion of invalid data

Engineering Contradiction:

Improvedata completenessVSAvoidmigration target data volume

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent extracts only the necessary valid data portions from the source volume by analyzing thin provisioning information. This extraction process separates valid data from invalid data, ensuring that only valid data is included in the migration target, thus reducing the total migration data volume while maintaining data completeness for valid portions.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of migrating all data from the source volume (excessive action), the patent implements partial migration by selectively transferring only the valid data portions identified through thin provisioning information analysis. This partial action approach avoids the overhead of transferring invalid data while ensuring all necessary valid data is migrated.

Inventive Principle:

Principle #16Partial or excessive action

3Ease of operation

If physical pages are assigned to all virtual pages in the destination TP volume, then storage structure is established, but storage capacity is consumed even for virtual pages containing invalid data

Engineering Contradiction:

Improvestorage structure establishmentVSAvoidstorage capacity consumption

Core Design Contradiction:

Ease of operationVSQuantity of substance

Solution Approach 1:

The patent performs preliminary assignment of physical pages to virtual pages in the destination TP volume based on thin provisioning information from the source system. By analyzing which virtual pages contain valid data before migration, the system pre-plans physical page assignment only for those virtual pages that will receive valid data, avoiding unnecessary physical page allocation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extracts the necessary physical page assignment information from the source storage system's thin provisioning metadata. This extracted information guides the destination system to assign physical pages only to virtual pages that correspond to valid data, rather than assigning physical pages to all virtual pages indiscriminately.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8984248B2Data migration system and data migration method

Publication Date: 2015.03.17 HITACHI VANTARA LTD

AI summary

A second storage maps a migration source volume to a virtual volume of a migration destination volume according to storage virtualization technology. A host system including a host switches an access path from an access path to the migration source volume to an access path to the migration destination volume. The second storage executes copy processing of migrating, from the migration source volume to the migration destination volume, data in an assigned area of a virtual volume according to thin provisioning of the migration source volume based on the information contained in the first thin provisioning information in the first storage, and copying that data from the migration destination volume to a virtual volume according to thin provisioning of a copy destination volume in the second storage. The second storage associates the virtual volume of the copy destination volume with the migration destination volume in substitute for the original virtual volume.