Cache Management for Data Migration Metadata
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Solution Overview
Problem
Current data storage systems face inefficiencies in caching metadata (MD) pages during data migration or replication, leading to suboptimal cache utilization and increased processing times due to the lack of a structured approach for loading and unloading MD pages based on access patterns.
Innovation Solution
A method involving a hierarchical structure of MD pages, where a depth-first traversal sequence is used to determine when to load and remove MD pages from the cache, optimizing cache management by ensuring that only necessary MD pages are retained until their child nodes have been processed, and allowing for prefetching to improve data access efficiency during migration or replication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If MD pages are loaded into cache during data migration or replication, then data access efficiency is improved, but cache utilization becomes suboptimal and processing time increases due to lack of structured cache management
Solution Approach 1:
The patent applies preliminary action by determining a depth-first traversal sequence of MD pages before the actual data migration or replication process. This sequence is used to proactively load the required MD pages into cache in advance, ensuring that when data access occurs during migration, the necessary metadata is already available in cache, thereby improving data access efficiency while avoiding unnecessary cache operations that would increase processing time
2Speed
If all MD pages are retained in cache during migration, then data access efficiency is improved, but cache utilization becomes suboptimal
Solution Approach 1:
The patent applies segmentation by dividing the MD pages into a hierarchical structure based on depth-first traversal sequence. Instead of treating all MD pages uniformly, the system segments them into groups that will be accessed together during the migration process, loading only the necessary segments into cache at appropriate times. This selective loading approach improves cache utilization by ensuring that cache space is dedicated to MD pages that will actually be needed, rather than retaining all possible MD pages
Solution Approach 2:
The depth-first traversal sequence enables preliminary determination of which MD pages need to be loaded into cache and when they should be removed. By knowing the access pattern in advance, the system can load MD pages into cache just before they are needed and remove them after use, optimizing cache utilization while maintaining data access efficiency
Data Source
AI summary
Techniques for processing data include: receiving a hierarchical structure of metadata (MD) pages for a logical device; and performing processing to copy data of the logical device from a source system to a target system. The first processing includes: determining a sequence of the MD pages in accordance with a depth first traversal of the hierarchical structure; defining a cache management policy in accordance with the sequence that indicates when to load the MD pages into a cache and when to remove the MD pages from the cache; loading MD pages into, and removing MD pages from, the cache in accordance with the cache management policy; and copying data pages stored at logical addresses of the logical device in an order in which the logical addresses are accessed using MD pages stored in the cache at various points in time in accordance with the cache management policy.