Distributed Storage Recovery Using Encoded Slice Rebuilding
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Solution Overview
Problem
Existing data storage systems lack effective means for recovering lost data and maintaining data integrity in the face of storage unit failures without the need for redundant copies.
Innovation Solution
A dispersed storage network (DSN) utilizing dispersed storage error encoding and decoding, managed by a managing unit and integrity processing unit, which encodes data into multiple encoded data slices stored across geographically diverse units, allowing recovery through rebuilding or repairing missing slices using available slices, and employing an External Healing Mode to manage data loss scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored using traditional RAID or dispersed storage systems, then data redundancy and availability are improved, but the ability to recover lost data effectively is insufficient
Solution Approach 1:
The system performs preliminary actions by continuously monitoring storage unit health and proactively identifying at-risk data slices before complete failure occurs. The integrity processing unit detects degradation patterns and triggers preventive repair operations, rebuilding replacement slices before the original data is lost, thus preventing data loss rather than just recovering it.
Solution Approach 2:
The system implements feedback mechanisms where the integrity processing unit continuously monitors storage units for errors and degradation. When issues are detected, the system automatically triggers repair operations and updates the data map. This closed-loop feedback ensures that data integrity is maintained through continuous monitoring and automatic correction of emerging problems.
2Reliability
If multiple encoded data slices are distributed across geographically diverse storage units, then data security and fault tolerance are improved, but system complexity increases
Solution Approach 1:
The integrity processing unit serves as an intermediary that simplifies the complex interactions between distributed storage units. It centralizes the monitoring, error detection, and repair coordination functions, managing the geographically distributed slices without requiring each storage unit to independently handle complex recovery protocols. This intermediary layer abstracts the complexity while maintaining fault tolerance.
Solution Approach 2:
The system segments data into multiple encoded slices distributed across different geographic locations, with each slice being independently manageable. The data map divides the system into manageable units (storage units, slices, pillars) that can be independently monitored and repaired. This segmentation allows complex distributed storage to be managed through simpler, modular components.
3Reliability
If continuous monitoring and repair operations are performed on stored data, then data integrity is maintained, but processing time and resource consumption increase
Solution Approach 1:
The integrity processing unit performs monitoring and repair operations periodically rather than continuously. It schedules regular integrity checks and repair operations at optimal intervals, balancing data integrity maintenance with resource consumption. This periodic approach ensures data integrity is maintained while avoiding the excessive processing time and resource usage that would result from continuous operations.
Data Source
AI summary
A computing device includes an interface configured to interface and communicate with a storage network (SN), a memory that stores operational instructions, and a processing module operably coupled to the interface and memory such that the processing module, when operable within the computing device based on the operational instructions, is configured to perform various operations. Based on a detected storage error, the computing device is configured to determine availability status of encoded data slices (EDSs) within a set of EDSs. When at least a decode threshold number of EDSs are available, the computing device is configured to initiate a rebuilding function to abate the detected storage error. When less than a decode threshold number of EDSs are available, the computing device is configured to initiate a data recovery function for at least one storage unit (SU) to abate the detected storage error.