Dynamic Allocation Unit Sizing for Compressed Data Storage
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Solution Overview
Problem
High capacity data storage systems face inefficiencies due to data compression, as compressed data often requires relocation when its size changes, leading to increased fragmentation and relocation overhead, which offsets the benefits of using multiple reduced size allocation units.
Innovation Solution
A compressed data manager that selects and monitors full-size and reduced-size allocation units based on changes in compressed data size over time, using weighted values to optimize storage, thereby reducing data relocation and fragmentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data compression is applied to reduce storage capacity requirements, then storage efficiency is improved, but data relocation frequency increases due to size changes
Solution Approach 1:
The patent implements dynamic allocation units that can change size based on the actual compressed data size. Instead of using fixed-size allocation units, the system adjusts the allocation unit size to match the compressed data size, thereby eliminating the need for relocation when compression ratios change. This dynamic adaptation resolves the contradiction by allowing compression benefits while avoiding frequent relocations.
Solution Approach 2:
The system changes the parameter of allocation unit size from a fixed value to a variable that adapts to compression characteristics. By monitoring compression ratios and adjusting allocation unit sizes accordingly, the system maintains optimal storage efficiency without triggering data relocation operations.
2Quantity of substance
If multiple reduced size allocation units are used to optimize compressed data storage, then storage efficiency is improved, but system complexity increases
Solution Approach 1:
The patent applies different allocation unit sizes to different data segments based on their local compression characteristics. Each data segment is assigned an allocation unit size that matches its specific compression ratio, rather than using a universal allocation unit size. This localized optimization improves storage efficiency without requiring a complex multi-size allocation system across the entire storage device.
3Ease of operation
If fixed size allocation units are used for compressed data, then management simplicity is maintained, but disk fragmentation increases
Solution Approach 1:
The system transitions from static fixed-size allocation units to dynamic allocation units that adapt to compressed data sizes. This dynamic approach maintains management simplicity through automated size adjustment while significantly reducing disk fragmentation by matching allocation unit sizes to actual data sizes.
4Quantity of substance
If compression is applied to infrequently accessed data, then storage capacity is optimized, but access latency increases
Solution Approach 1:
The patent implements different compression and allocation strategies for different data access patterns. Frequently accessed data is stored with larger allocation units or in uncompressed form for rapid access, while infrequently accessed data uses compressed storage with optimized allocation units. This localized quality differentiation optimizes storage capacity without significantly impacting access latency for critical data.
Data Source
AI summary
In a data storage system in which a full-size allocation unit is used for storage of uncompressed data, an optimal reduced size allocation unit is selected for storage of compressed data. Changes in the compressed size of at least one full-size allocation unit of representative data are monitored over time. The representative data may be selected based on write frequency, relocation frequency, or both. Compression size values are counted and weighted to calculate the optimal reduced allocation unit size. The optimal reduced size allocation unit is used for storage of compressed data. A full-size allocation unit of data that cannot be accommodated by a reduced size allocation unit when compressed is stored uncompressed.