Disk Deduplication Using Sequential Block Thresholds to Reduce Seek Latency
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Solution Overview
Problem
Conventional deduplication methods on disk devices cause significant read latency due to frequent seek operations between different tracks, as they deduplicate data on a single-block basis, leading to increased seek times when retrieving redundant blocks from different tracks.
Innovation Solution
Implementing deduplication based on a threshold number (THN) of sequential blocks, where a series of THN or more received blocks are matched against stored blocks, allowing for deduplication and reducing the number of seeks by storing and retrieving blocks in sequences, thereby mitigating read latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If deduplication is performed on a single-block basis, then storage space is saved by removing redundant data, but read latency increases due to frequent seek operations between different tracks
Solution Approach 1:
The patent merges multiple single-block deduplication operations into a single batch operation. Instead of processing each block individually and performing separate seek operations, the system collects multiple blocks into a batch and processes them together in one seek operation, reducing the total number of seeks and improving read latency while maintaining storage space savings
Solution Approach 2:
The patent performs preliminary actions by pre-fetching and caching metadata information about stored blocks before actual read operations. This allows the system to determine which blocks are redundant in advance and prepare batch deduplication operations, reducing the need for frequent seek operations during actual data retrieval
Data Source
AI summary
Deduplication of data on disk devices based on a threshold number (THN) of sequential blocks is described herein, the threshold number being two or greater. Deduplication may be performed when a series of THN or more received blocks (THN series) match a sequence of THN or more stored blocks (THN sequence), whereby a sequence comprises blocks stored on the same track of a disk device. Deduplication may be performed using a block-comparison mechanism comprising metadata entries of stored blocks and a mapping mechanism containing mappings of deduplicated blocks to their matching blocks. The mapping mechanism may be used to perform later read requests received for the deduplicated blocks. The deduplication described herein may reduce the read latency as the number of seeks between tracks may be reduced. Also, when a seek to a different track is performed, the seek time cost is spread over THN or more blocks.