Deduplication Restore Throughput Prioritization With Multi-Stream Read-Ahead
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Solution Overview
Problem
Existing backup systems lack efficient mechanisms to prioritize high-priority file restorations, leading to suboptimal resource utilization and prolonged restoration times.
Innovation Solution
Implementing a multi-stream restore (MSR) mechanism with multiple internal threads that prefetch data into a read-ahead cache, allowing for parallel data retrieval and prioritization of high-priority restorations while managing resource usage through a system load monitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple internal threads are used to prefetch data into read-ahead cache for high-priority file restoration, then restoration speed is improved, but system resource consumption increases
Solution Approach 1:
The system dynamically adjusts the number of internal threads used for prefetching based on system load conditions. When system resources are abundant, more threads are allocated to achieve faster restoration. When system load is high, the number of threads is reduced to prevent resource exhaustion. This dynamic adaptation resolves the contradiction by making resource usage flexible rather than fixed.
Solution Approach 2:
The system changes operational parameters (number of threads, prefetch size, cache allocation) based on system conditions to optimize the balance between restoration speed and resource consumption. By adjusting these parameters dynamically, the system can achieve fast restoration when possible while conserving resources when system load is high.
2Productivity
If multiple concurrent file restorations are allowed, then overall productivity is improved, but system load increases leading to potential overload
Solution Approach 1:
The system continuously monitors system load and uses this feedback to adjust the number of concurrent restoration operations allowed. When system load exceeds thresholds, the system automatically reduces the number of concurrent operations or prioritizes certain restorations over others. This feedback mechanism prevents system overload while maintaining high productivity when resources are available.
Solution Approach 2:
The system dynamically controls the number of concurrent restoration operations based on real-time system conditions. Instead of allowing a fixed number of concurrent operations, the system adapts this parameter dynamically, increasing concurrency when resources are abundant and reducing it when system load is high, thus maintaining both productivity and stability.
3Loss of time
If high-priority restorations are given preferential treatment with multiple threads, then restoration time for critical files is reduced, but resource allocation becomes uneven
Solution Approach 1:
The system applies different resource allocation strategies to different restoration operations based on their priority. High-priority files receive preferential treatment with more threads and cache allocation, while low-priority files receive standard or reduced resources. This local differentiation resolves the contradiction by optimizing restoration time for critical files without completely starving other operations, maintaining overall system productivity.
Data Source
AI summary
Multiple internal read-ahead streams are established for each of a set of current restore streams handling restorations of files managed by a deduplication filesystem. An API signature is received from a client. The signature includes an identification of a file to restore and a request to pin the file as priority. A restore stream for the file is tagged as priority requested. A determination of whether to establish multiple internal read-ahead streams for the restore stream includes when a threshold number of current restore streams using the multiple internal read-ahead streams has been reached, checking whether a current restore stream using the multiple internal read-ahead streams has the priority requested tag. When the current restore stream using the multiple internal read-ahead streams does not have the priority requested tag, the multiple internal read-ahead streams of the current restore streams are torn down.