Overlay Storage for File System Failure Handling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing data storage systems face challenges in managing device failures within object-based data storage subsystems, particularly in maintaining data redundancy and handling failures without burdening clients, while ensuring continuous read and write operations and minimizing data loss.
Innovation Solution
A computer system with a storage subsystem that includes a coordinating storage device to manage redundant data, detect failures, and configure an overlay storage device to temporarily replace failed regions, maintaining records of changes and resynchronizing data upon recovery, using erasure-coded layouts like RAID-5 or RAID-6 to ensure data integrity and availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clients are responsible for maintaining data redundancy and handling device failures, then data integrity can be maintained, but client complexity and computational overhead increase significantly
Solution Approach 1:
The patent extracts the complexity of maintaining data redundancy and handling device failures from the client system and relocates it to the storage subsystem. The storage subsystem independently manages erasure coding, parity calculation, and failure recovery operations, while clients simply perform read and write operations without needing to understand or manage the underlying redundancy mechanisms.
Solution Approach 2:
The storage subsystem acts as an intermediary between clients and the physical storage devices. It manages the complexity of redundancy maintenance and failure handling internally, presenting a simplified interface to clients while ensuring data integrity through coordinated operations across multiple storage devices.
2Reliability
If RAID layouts are implemented with clients responsible for maintaining redundancy, then fault tolerance is improved, but write latency increases due to additional computational overhead
Solution Approach 1:
The storage subsystem performs self-service by automatically calculating parity, managing redundancy, and handling failure recovery without requiring client intervention. This eliminates the computational overhead that would otherwise be performed by clients, reducing write latency while maintaining fault tolerance through coordinated operations within the storage subsystem.
3Reliability
If overlay storage devices are used to replace failed regions, then continuous operation is maintained, but device complexity increases
Solution Approach 1:
The patent uses overlay storage devices that create virtual copies or representations of failed storage regions. These overlay devices allow the system to continue operating by redirecting I/O operations to healthy storage devices while maintaining the appearance of the failed device being operational. The complexity of managing these overlays is handled automatically by the storage subsystem's coordination logic.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A system and method for data storage in an array. A system includes a client coupled to a storage subsystem including data storage locations addressable as rows and columns in an array. Each column comprises a separate storage device. Each row includes redundant data. For a given row, a coordinating storage device coordinates the computation and storage of redundant data. The system detects a failure of a storage region and in response, configures an overlay storage device to temporarily overlay the failed region, maintains an association between the overlay device and the failed region, and maintains a record of changes made to the overlay device while the region is in a failed state. In response to detecting that the failed region has been restored, the system uses the association to identify the overlay device and uses the record of changes made to the overlay device to resynchronize the failed region.