In-Chunk Index for Partial File Restore
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Solution Overview
Problem
Current data storage systems face challenges in efficiently restoring partial files from secondary storage, as application offsets do not directly map to secondary copy offsets due to metadata and deduplication, leading to inefficiencies in accessing specific portions of files.
Innovation Solution
Implementing an in-chunk index that maps application offsets to secondary copy offsets, allowing for efficient access and restoration of file portions by organizing data into logical chunks with associated metadata, facilitating quick location and retrieval of desired file parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If application offsets are used to access file portions, then user interface simplicity is improved, but mapping accuracy to secondary copy offsets deteriorates due to metadata and deduplication
Solution Approach 1:
The patent introduces an intermediary mapping mechanism that translates application offsets to secondary copy offsets. This intermediary layer handles the complexity of metadata and deduplication transformations, allowing users to work with simple application offsets while the system accurately maps them to the actual secondary storage locations through intermediate calculation steps.
2Reliability
If entire secondary copies are restored, then data completeness is improved, but restoration time increases significantly
Solution Approach 1:
The patent segments the restoration process by enabling selective restoration of specific file portions rather than requiring complete file restoration. Users can specify start and end offsets to restore only the needed segments, dividing the large-scale restoration task into smaller, manageable portions that can be restored independently and more quickly.
Solution Approach 2:
The patent applies partial action by restoring only the necessary portion of the file rather than the entire secondary copy. This allows the system to perform exactly the amount of restoration needed - no more, no less - thereby reducing restoration time while maintaining data completeness for the required portions.
3Measurement precision
If detailed mapping information is stored for all file portions, then access accuracy is improved, but index size and storage requirements increase
Solution Approach 1:
The patent performs preliminary calculations during the backup process to establish offset mapping relationships. By pre-computing and storing essential mapping information during backup, the system reduces the need for extensive real-time calculations and large index structures during restoration, maintaining access accuracy while minimizing stored index data.
Data Source
AI summary
The data storage system according to certain aspects can implement partial file restore, where only a portion of the secondary copy of a file is restored. Such portion may be designated by one or more application offsets for the file. The system may provide an in-chunk index that includes mapping information between the application offsets and the secondary copy offsets. Chunks may refer to logical data units in which secondary copies are stored, and the in-chunk index for a chunk may be stored in secondary storage with the chunk. Because the mapping information may not be provided at a fixed interval, the system can search through application offsets in the in-chunk index to locate the secondary copy offset corresponding to the portion application offset(s). In this manner, the system may restore the designated portion of the secondary copy in a fast and efficient manner by using the in-chunk index.