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There isn't really a coherent development plan for this tool. It is more of a proving ground for various bees concepts, and occasionally useful for spot dedupe of single large files that are known to be mostly duplicate. It's published here because occasionally a few lines of this code become useful for explaining to people how to implement better tools. In particular, btrsame has no concept of btrfs's requirements for extent splitting, so it will be ineffective as a dedupe tool for files that are similar but not entirely identical. Not only that, btrsame may also create a potentially large number of unreachable blocks in the process. Change summary: - opens files O_RDONLY when using dedupe_file_range ioctl - drop the code that implements the contiguous differences threshold. - shorten status line by pretty-printing numbers with a unit suffix - don't throw an error exception while in the process of formatting a message about the error - use readahead to work around dedupe ioctl behavior - remove random notes about now-long-dead lockup bugs - remove long dead commented out file reference lookup tool Signed-off-by: Zygo Blaxell <bees@furryterror.org>
BEES
Best-Effort Extent-Same, a btrfs deduplication agent.
About bees
bees is a block-oriented userspace deduplication agent designed for large btrfs filesystems. It is an offline dedupe combined with an incremental data scan capability to minimize time data spends on disk from write to dedupe.
Strengths
- Space-efficient hash table and matching algorithms - can use as little as 1 GB hash table per 10 TB unique data (0.1GB/TB)
- Daemon incrementally dedupes new data using btrfs tree search
- Works with btrfs compression - dedupe any combination of compressed and uncompressed files
- NEW Works around
btrfs sendproblems with dedupe and incremental parent shapshots - Works around btrfs filesystem structure to free more disk space
- Persistent hash table for rapid restart after shutdown
- Whole-filesystem dedupe - including snapshots
- Constant hash table size - no increased RAM usage if data set becomes larger
- Works on live data - no scheduled downtime required
- Automatic self-throttling based on system load
Weaknesses
- Whole-filesystem dedupe - has no include/exclude filters, does not accept file lists
- Requires root privilege (or
CAP_SYS_ADMIN) - First run may require temporary disk space for extent reorganization
- First run may increase metadata space usage if many snapshots exist
- Constant hash table size - no decreased RAM usage if data set becomes smaller
- btrfs only
Installation and Usage
Recommended Reading
- bees Gotchas
- btrfs kernel bugs - especially DATA CORRUPTION WARNING
- bees vs. other btrfs features
- What to do when something goes wrong
More Information
Bug Reports and Contributions
Email bug reports and patches to Zygo Blaxell bees@furryterror.org.
You can also use Github:
https://github.com/Zygo/bees
Copyright & License
Copyright 2015-2018 Zygo Blaxell bees@furryterror.org.
GPL (version 3 or later).