Data Migration Source Device Reuse via Diversion Flag
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Solution Overview
Problem
Existing data storage migration systems require maintaining the source device until all applications have terminated, preventing the reuse of the source device until all applications have closed, which leads to inefficiencies in capacity utilization and performance enhancement.
Innovation Solution
The system maps application address spaces to metadata for the target device, sets a diversion flag to remap extents, and closes and unallocates the data set at the source device, allowing for the reuse of the source device before all applications terminate, by providing additional local metadata that includes addresses for both source and target devices and managing I/O operations to divert data to the target device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source device is maintained until all applications terminate, then data migration can be completed safely, but the source device cannot be reused and capacity utilization is reduced
Solution Approach 1:
The patent segments the data set into migrated and non-migrated portions, allowing the source device to be partially released and reused while maintaining migration safety through controlled divergence of I/O operations. This enables capacity utilization improvement without compromising migration reliability.
Solution Approach 2:
The patent introduces an intermediary mechanism (diversion flag and I/O handling logic) that mediates between the source device and applications, allowing safe divergence of I/O operations and enabling source device reuse while maintaining data migration safety.
2Quantity of substance
If the source device is maintained until all applications terminate, then all data can be migrated, but the source device remains occupied and cannot support new workloads
Solution Approach 1:
The patent makes the source device status dynamic by allowing it to transition from fully occupied to partially available during migration. The diversion flag mechanism enables the source device to adapt its availability state, supporting new workloads while completing data migration.
Solution Approach 2:
The patent performs preliminary action by setting the diversion flag before all applications terminate, allowing the source device to be prepared for reuse while migration continues. This enables the source device to become available for new workloads without completing all data migration first.
3Productivity
If application address space is remapped to target device metadata, then I/O operations can be diverted, but additional metadata management complexity is introduced
Solution Approach 1:
The patent applies local quality by introducing additional local metadata only where needed for migration divergence, rather than modifying the entire metadata structure. This enables efficient I/O diversion while minimizing the impact on overall system complexity.
Data Source
AI summary
Releasing a data set at a source device in connection with migrating data from the source device to a target device includes mapping application address space to address space containing metadata for the target device and providing additional local metadata therefor, replacing within the application the address of metadata for the source device with the address of metadata for the target device, setting a diversion flag that is part of the additional local metadata, where the diversion flag indicates a remapping of extent, and closing and unallocating the data set at the source device. Releasing a data set at a source device in connection with migrating data from the source device to a target device may also include determining if an application uses standard I/O operations. The metadata may include UCB data.