Erofs – Enhanced Read-Only File System – The Linux Kernel Documentation
EROFS is an enhanced read-only file system that utilizes fixed-sized output compression for data. This method allows for higher compression ratios by leveraging historical dictionaries from popular LZ77-based algorithms. The system introduces logical clusters to manage variable-sized extents and supports big physical clusters for improved data handling.
- ▪EROFS implements fixed-sized output compression generating fixed-sized compressed data blocks from variable-sized input.
- ▪The introduction of big pclusters allows for multiple variable-sized extents to be used for compressed data deduplication.
- ▪Logical clusters are used to indicate whether a new extent is generated within a specified range.
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Data compression¶ EROFS implements fixed-sized output compression which generates fixed-sized compressed data blocks from variable-sized input in contrast to other existing fixed-sized input solutions. Relatively higher compression ratios can be gotten by using fixed-sized output compression since nowadays popular data compression algorithms are mostly LZ77-based and such fixed-sized output approach can be benefited from the historical dictionary (aka. sliding window). In details, original (uncompressed) data is turned into several variable-sized extents and in the meanwhile, compressed into physical clusters (pclusters).
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