Storage Migration Metadata Mapping Host Offload
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Solution Overview
Problem
Existing data migration systems require significant data to pass through the host processor, which can be impractical due to data volume and is less than optimal, especially when replacing storage devices without disrupting host operations while maintaining disaster recovery capabilities.
Innovation Solution
The system migrates data from a first storage device to a second by modifying metadata to change the mapping of logical devices to physical devices, allowing independent data transfer without host involvement, and acknowledges writes only after data is successfully written to both devices, enabling data to be copied from the first storage device to the second before host writes, thus reducing the need for data to pass through the host.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data migration is performed through the host processor, then data can be transferred from the first storage device to the second storage device, but the host processor becomes a bottleneck and operations are disrupted
Solution Approach 1:
The patent extracts the data migration function from the host processor by implementing a dedicated data migration path between storage devices. The host processor is removed from the critical data transfer path, allowing migration to occur independently through direct storage-to-storage communication or through dedicated migration hardware, thus eliminating the bottleneck while maintaining host operation continuity.
Solution Approach 2:
The patent introduces an intermediary mechanism (storage device controller or dedicated migration hardware) that mediates the data transfer between storage devices. This intermediary handles the data migration tasks without involving the host processor, allowing the host to continue its operations uninterrupted while data is migrated in the background through the intermediary component.
2Reliability
If data is written to both storage devices before acknowledgment, then disaster recovery position is maintained, but write operation latency increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring the dual-write mechanism and metadata structures before actual data migration begins. The system prepares the acknowledgment logic and data paths in advance, so that during operation, data can be written to both storage devices and acknowledged efficiently without extensive processing delays, maintaining both reliability and acceptable latency.
3Adaptability or versatility
If metadata mapping is modified to redirect I/O operations, then logical device to physical device mapping changes, but system consistency must be maintained
Solution Approach 1:
The patent implements feedback mechanisms that continuously monitor and verify the consistency of metadata mappings and data integrity after modifications. The system provides feedback loops that detect inconsistencies in the logical-to-physical device mapping and trigger corrective actions, ensuring that adaptability in reconfiguring storage mappings does not compromise system consistency or data integrity.
Data Source
AI summary
Migrating data from a first storage device to a second storage device includes coupling a host computer to the storage devices, causing the host computer to transition from performing I/O operations with the first storage device to performing I/O operations with the second storage device by modifying metadata used for I/O operations to change a mapping of logical devices to physical devices, migrating data from the first storage device to the second storage device independently of any I/O operations by the host, and acknowledging a data write operation from the host only after the data has been successfully written to both the first storage device and the second storage device. Modifying metadata may include changing control block information in device drivers. The data may be written by the host to the second storage device only and the data may be copied from the second storage device to the first storage device.