SMR-Aware Append-Only File System Circular Linked List
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Solution Overview
Problem
Shingled magnetic recording (SMR) technology in disk drives faces challenges in efficiently managing append-only data storage, particularly in host-aware SMR drives where random write capabilities are limited, leading to inefficiencies in data organization and storage density.
Innovation Solution
A SMR-aware append-only file system is developed, utilizing a circular linked list of concentric data bands with a head and tail data band, where new data blocks are appended to the tail, and when a threshold is reached, data blocks from the head band are copied to a new file, optimizing storage by compacting data into contiguous segments and reducing fragmentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a SMR translation layer is used to enable random write capabilities, then write flexibility is improved, but device complexity and storage density efficiency deteriorate
Solution Approach 1:
The patent extracts and removes the SMR translation layer from the system, designing an append-only file system that directly utilizes SMR drive characteristics without requiring translation services. This eliminates the complexity introduced by translation layers while maintaining compatibility with SMR's append-only nature.
Solution Approach 2:
Instead of trying to enable random writes on append-only SMR bands through translation layers, the patent inverts the approach by designing a file system that embraces the append-only constraint and organizes data structures accordingly, achieving efficiency without the translation layer overhead.
2Quantity of substance
If data blocks are scattered across multiple SMR bands, then storage capacity is utilized, but sequential read performance and write head movement efficiency deteriorate
Solution Approach 1:
The patent segments the file system into a circular linked list of SMR bands, where each band contains contiguous data blocks. This segmentation allows the file system to utilize multiple bands for storage capacity while maintaining sequential read performance by keeping data contiguous within each band.
Solution Approach 2:
The patent merges multiple SMR bands into a unified circular linked list structure, allowing efficient sequential access across bands. The circular linked list enables the write head to move continuously through bands in a unified manner, improving write head movement efficiency while maintaining storage capacity across multiple bands.
3Quantity of substance
If a circular linked list of data bands is used for append-only storage, then storage density and sequential read performance are improved, but data organization complexity increases
Solution Approach 1:
The patent implements a dynamic circular linked list structure where data bands can be added, removed, and reorganized as needed. This dynamic structure allows the system to adapt to varying storage needs while maintaining high storage density and managing data organization complexity through flexible structure manipulation.
Solution Approach 2:
The circular linked list structure enables continuous sequential access across data bands without interruption. The circular nature allows the read/write head to continuously traverse bands in sequence, maintaining useful action continuity and improving sequential read performance while managing data organization through a unified continuous structure.
4Productivity
If empty data bands are immediately allocated to new files, then file creation speed is improved, but fragmentation and storage efficiency worsen
Solution Approach 1:
The patent implements preliminary action by pre-organizing empty data bands in the circular linked list and maintaining a structure that allows efficient allocation. When a new file is created, empty bands are allocated from the circular list in a controlled manner, improving file creation speed while preventing fragmentation through systematic allocation management.
Data Source
AI summary
A shingled magnetic recording (SMR) append-only file system includes a disk comprising a plurality of concentric append-only shingled data bands having partially overlapping data tracks, wherein the data bands are associated with a circular linked list having a head data band and a tail data band, the head data band and the tail data band each comprising a plurality of data blocks. The system also includes a processor configured to write data blocks to the disk, and create a new file wherein an empty data band of the plurality of data bands is removed from the circular linked list and added to a single linked list of the new file.