Distributed File System Metadata Update During Site Cache Flush
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Solution Overview
Problem
Distributed file systems face performance degradation due to geographically diverse data storage, and site caches complicate disaster recovery by potentially providing incorrect location information if flushed between backups.
Innovation Solution
Implementing a site cache at client sites with high bandwidth, low latency connections to process IO requests efficiently, while maintaining centralized metadata for location information and using methods to correctly update metadata during site cache flushing and disaster recovery processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If site cache is implemented to improve access performance, then client access speed is improved, but disaster recovery reliability deteriorates due to potential incorrect location information
Solution Approach 1:
The system segments storage into two independent components: site cache for local performance and centralized metadata for authoritative location information. The metadata server maintains separate tracking of cached objects versus actual storage locations, preventing cache flush operations from corrupting disaster recovery metadata.
Solution Approach 2:
The metadata server acts as an intermediary between site cache and centralized storage. It mediates location information by maintaining independent records of which objects are cached and their corresponding actual locations, ensuring that cache operations do not interfere with disaster recovery metadata accuracy.
2Measurement precision
If site cache is flushed to update location information, then metadata accuracy is improved, but system complexity increases due to coordination requirements
Solution Approach 1:
The system separates cache management functions from metadata management functions. The site cache handles local performance optimizations independently, while the metadata server maintains authoritative location records separately. This segmentation eliminates the need for complex coordination during cache flush operations.
Solution Approach 2:
The site cache self-manages its own objects without requiring metadata server intervention during flush operations. The metadata server passively tracks location information without needing to coordinate with cache flush timing, simplifying the overall system architecture.
Data Source
AI summary
A snapshot is received at the MDS from a backup storage location at a point-in-time subsequent to taking the snapshot, wherein the MDS comprises a map identifying an object store location for a plurality of data objects and a queue identifying individuals of the plurality of data objects that only reside on the transient object store. Individuals of the plurality of data objects identified in the queue are located on the distributed file system. The map is updated to identify the object store location for the individuals of the plurality of data objects identified in the queue.