Virtual Disk Migration Using Cross-Pool Data Deduplication
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Solution Overview
Problem
When migrating a virtual disk between pool areas in a storage apparatus, existing technologies require transferring all data to the new pool area and re-executing duplicate removal, leading to increased processing load and inefficiency.
Innovation Solution
A storage system and method that perform duplicate determination between the source and destination pool areas, allowing only non-duplicate data to be migrated, thereby reducing processing load and eliminating the need for data restoration and re-execution of duplicate removal processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all data is transferred to the new pool area during virtual disk migration, then complete data migration is achieved, but processing load increases and migration time extends
Solution Approach 1:
The system performs duplicate determination in advance by calculating hash values of data blocks in the source pool area and comparing them with hash values of blocks in the destination pool area. This preliminary action identifies which blocks are duplicates before the actual migration begins, allowing the system to transfer only non-duplicate blocks and skip redundant data transfer operations.
Solution Approach 2:
The invention extracts only the necessary data blocks for migration by identifying and excluding duplicate blocks. Instead of transferring all data blocks from the source pool area to the destination pool area, the system calculates hash values, compares them against the destination pool, and extracts only those blocks that do not already exist in the destination, thereby reducing migration volume and processing load.
2Reliability
If duplicate removal is re-executed after migration, then data deduplication is maintained, but processing time and system load increase
Solution Approach 1:
The system performs duplicate determination as a preliminary step before migration by calculating hash values of source data blocks and comparing them with hash values already present in the destination pool area. This advance identification of duplicates eliminates the need for post-migration duplicate removal operations, as the migration process itself ensures deduplication integrity from the start.
3Measurement precision
If hash value comparison is performed for all data blocks, then accurate duplicate detection is achieved, but processing load increases
Solution Approach 1:
Instead of comparing actual data block contents, the system uses hash values (digital fingerprints) as copies or representations of the data blocks for comparison purposes. This approach maintains high duplicate detection accuracy because hash functions produce unique values for different data, while dramatically reducing processing load since comparing hash values is much faster and less resource-intensive than comparing actual data block contents.
Data Source
AI summary
Provided are a storage apparatus, a storage system, and a data migration method, with which a plurality of pool areas are assigned to a plurality of virtual volumes, the virtual volumes comprise virtual disks, the virtual disks comprise a plurality of logical segments, the pool areas comprise real volumes, the real volumes comprise a plurality of physical segments, logical segments are managed in association with physical segments, for each of the plurality of pool areas, and, if one virtual disk which is associated with one pool area is migrated to another pool area which differs from the one pool area, duplicate determination of data in the one pool area is executed, a data duplicate determination between the one pool area and the other pool area is executed on the basis of the result of the duplicate determination, and the one virtual disk is migrated to the other pool area.