Compressed Segment Reorganization for Inline File System Compression
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Solution Overview
Problem
Existing file system reorganization techniques face inefficiencies in storage systems with inline compression, leading to hidden fragmentation and poor space savings due to inadequate handling of compressed data and metadata, resulting in performance bottlenecks and resource wastage.
Innovation Solution
The method involves obtaining a virtual block pointer for a compressed segment, copying referenced allocation units to a new segment, updating metadata to reflect the new location, and freeing the original segment, with optional in-place compaction to reclaim space when relocation is not feasible, thereby reusing data fragments and reducing processing load on scavenging utilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional file system reorganization techniques are used in storage systems with inline compression, then the reorganization process can be performed, but hidden fragmentation occurs and space savings are reduced due to inadequate handling of compressed data and metadata
Solution Approach 1:
The patent segments the reorganization process into distinct phases: identifying referenced allocation units within compressed segments, copying only those referenced units to new locations, and freeing original segments. This segmentation allows precise handling of compressed data structures, avoiding unnecessary copying of unreferenced data and thereby preserving space savings while enabling effective reorganization.
Solution Approach 2:
The patent applies local quality by treating referenced and unreferenced allocation units differently within the same compressed segment. Referenced units are copied and preserved, while unreferenced units are left in place or freed. This differential treatment optimizes space utilization by maintaining only necessary data copies and eliminating redundancy, thus improving space savings without compromising reorganization effectiveness.
2Ease of manufacture
If traditional file system reorganization techniques are used in storage systems with inline compression, then the reorganization process can be performed, but performance bottlenecks occur due to inadequate handling of compressed data and metadata
Solution Approach 1:
The patent extracts and processes only the referenced allocation units from compressed segments during reorganization, rather than handling entire segments or all allocation units. This extraction approach reduces the volume of data and metadata that must be processed, eliminating performance bottlenecks while maintaining complete reorganization functionality for all necessary files.
Solution Approach 2:
The patent performs preliminary identification of referenced allocation units before executing the copy operation. By pre-processing the metadata to determine which allocation units are actually referenced by files in the file system, the system prepares an optimized work list that avoids unnecessary processing steps, thereby improving reorganization performance without sacrificing thoroughness.
3Ease of manufacture
If traditional file system reorganization techniques are used in storage systems with inline compression, then the reorganization process can be performed, but resource wastage occurs due to inadequate handling of compressed data and metadata
Solution Approach 1:
The patent applies partial action by performing reorganization operations only on referenced allocation units rather than all allocation units in compressed segments. This partial processing approach reduces the processing load and resource consumption while still achieving complete reorganization of all files that need to be reorganized, eliminating resource wastage without compromising reorganization effectiveness.
Data Source
AI summary
A method for file system reorganization in the presence of inline compression includes obtaining a virtual block pointer for an original compressed segment to be reorganized, the original compressed segment comprising compressed allocation units of data stored in a storage system, wherein the virtual block pointer comprises an extent list identifying the compressed allocation units in the original compressed segment and a pointer to where the original compressed segment is stored; copying only the referenced compressed allocation units in the original compressed segment to a new compressed segment in a substantially contiguous manner; updating the extent list to identify the referenced compressed allocation units in the new compressed segment, and the pointer to where the new compressed segment is stored; and freeing the original compressed segment.