Thin-Provisioned Volume Migration in Tiered Storage
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Solution Overview
Problem
Tiered storage architectures often fail to support the migration of thin-provisioned volumes between storage tiers, leading to inefficient storage utilization and increased costs due to unused allocated space.
Innovation Solution
A method and apparatus that migrate volumes by identifying data extents requiring migration, allocating copiers to copy data units, and dynamically adjusting copier resources to manage destages, allowing for the conversion of standard volumes to thin-provisioned volumes during migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thin provisioning is implemented to allocate storage space on a just-enough and just-in-time basis, then storage utilization efficiency is improved, but the ability to migrate volumes between storage tiers is lost
Solution Approach 1:
The patent segments the thin-provisioned volume into multiple data extents that can be independently migrated. Each extent is treated as a separate unit that can be copied to target storage tiers, enabling migration of thin-provisioned volumes by processing their constituent extents individually rather than as a single monolithic volume.
Solution Approach 2:
The patent introduces an intermediary mapping structure that tracks the location of each extent's data. This mapping acts as a mediator between the thin-provisioned volume abstraction and the physical storage tiers, allowing the system to manage and migrate thin-provisioned volumes by updating extent mappings rather than physically moving entire volume structures.
2Adaptability or versatility
If storage space is allocated up front using conventional techniques, then volume migration is supported, but storage utilization efficiency deteriorates with large amounts of unused space
Solution Approach 1:
The patent implements dynamic extent allocation where storage space is allocated on-demand as data is written to thin-provisioned volumes. The system dynamically determines which extents contain actual data and migrates only those extents, rather than migrating pre-allocated empty space. This dynamic approach enables efficient migration of thin-provisioned volumes by adapting to actual data distribution.
3Speed
If copiers are allocated to migrate data extents, then migration speed is improved, but system complexity increases due to dynamic copier allocation and monitoring
Solution Approach 1:
The patent implements self-service mechanisms where the migration system automatically monitors destage rates and dynamically allocates additional copiers when needed. The system self-regulates by detecting when destages occur faster than copiers can copy data, then automatically provisioning additional copy resources without external intervention, reducing the need for complex manual monitoring and management.
Data Source
AI summary
A method for migrating volumes in a storage system includes identifying an extent of data (belonging to a volume) requiring migration from a source extent to a target extent. The method allocates a selected number of copiers to the extent of data to migrate the extent of data from the source extent to the target extent. Each copier is configured to copy a unit of data, which is a smaller division of the extent of data. The method monitors destages (i.e., writes) that occur to the source extent as the copiers migrate the extent of data from the source extent to the target extent. In the event the destages occur faster than the copiers can copy units to the target extent, the method allocates additional copiers to the extent of data to assist in migrating the extent of data. A corresponding apparatus and computer program product are also disclosed.