Deduplicated Data Restoration With Look-Ahead Read Caching
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Solution Overview
Problem
Existing data storage technologies, particularly those using cloud-based storage and multi-node replicated file systems, perform slowly when restoring deduplicated data due to inefficient interaction with storage media.
Innovation Solution
Implementing a pre-restore look-ahead reader that fetches deduplicated data in anticipation of read requests, identifies consecutive data segments (S File Runs), issues aggregated read requests, and caches data locally to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional storage technologies (cloud-based storage, multi-node replicated file systems) are used for storing deduplicated data, then scalability and reliability are improved, but restoration speed deteriorates
Solution Approach 1:
The patent applies preliminary action by implementing a look-ahead reader that proactively fetches data from storage media before it is actually needed during restoration. The system identifies consecutive data segments (S File Runs) and pre-loads them into a local buffer, so when restoration requests arrive, the data is already available locally, eliminating the slow network transfer delay and significantly improving restoration speed while maintaining the reliability benefits of cloud-based storage.
2Reliability
If individual read requests are issued for each data segment during restoration, then data integrity is ensured, but restoration time increases
Solution Approach 1:
The patent merges multiple individual read requests into a single aggregated read request by identifying consecutive data segments (S File Runs) that can be retrieved together. Instead of issuing separate read requests for each data segment, the system groups them into runs and issues one read request per run, loading all segments into a local buffer at once. This maintains data integrity through proper indexing while dramatically reducing restoration time by minimizing the number of I/O operations.
Solution Approach 2:
The look-ahead reader performs preliminary action by proactively fetching complete data segments into the local buffer before restoration is actually needed. The system analyzes the restore requirements, identifies which consecutive data segments will be needed, and pre-loads them into memory. This eliminates the need for multiple sequential read requests during restoration, reducing restoration time while ensuring data integrity through the indexing mechanism.
3Productivity
If data is fetched on-demand during restoration operations, then storage media interactions are minimized, but restoration performance deteriorates
Solution Approach 1:
The patent applies preliminary action through the look-ahead reader that proactively fetches data from storage media before restoration is actually needed. The system identifies consecutive data segments (S File Runs) and pre-loads them into a local buffer, so when restoration requests arrive, the data is already available locally. This shifts the storage media interaction to occur during the look-ahead phase rather than during restoration, improving both storage media interaction efficiency and restoration speed by eliminating sequential read delays.
Data Source
AI summary
Techniques disclosed herein are well suited to restoring deduplicated backup data from cloud-based storage and from multi-node replicated files systems, and they also improve performance in more traditional data storage technologies. Pre-restore steps include analysis of deduplication indexes to identify data segments that are stored consecutively on storage media. Reading data in aggregate runs of consecutively stored data segments reduces interactions with storage media that hosts the deduplicated data and speeds up retrieval. Parallel reads from multiple storage devices in multi-node replicated file systems also speed up retrieval. An illustrative enhanced media agent pre-fetches data (stored in deduplicated form) in anticipation of read requests that are expected in the restore operation. The pre-fetched data is temporarily stored locally at the media agent, which is responsible for interfacing with storage media and is further responsible for orchestrating the disclosed techniques within an illustrative data storage management system.