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e457f502b7
"Kernel" -> "Linux kernel". If you can run bees on a kernel that isn't Linux, congratulations! Emphasize the age of the data corruption warnings. Once 5.4 reaches EOL we can remove those. Simplify the discussion of old kernels and API levels. There's a new optional kernel API for `openat2` support at 5.6. The absolute minimum kernel version is still 4.2, and will not increase to 4.15 until the subvol scanners are removed. Remove discussion of bees support for kernels 4.19 (which recently reached EOL) and earlier. The `LOGICAL_INO` vs dedupe bug is actually a `LOGICAL_INO` vs clone bug. Dedupe isn't necessary to reproduce it. Remove a stray ')'. Strip out most of the discussion of slow backrefs, as they are no longer a concern on the range of supported kernel versions. Leave some description there because bees still has some vestigial workarounds. Remove `btrfs send` from the "Unfixed kernel bugs" section, which makes the section empty, so remove the section too. bees now handles send on a subvol reasonably well. 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 to scale up to 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 - can use as little as 1 GB hash table per 10 TB unique data (0.1GB/TB)
- Daemon mode - incrementally dedupes new data as it appears
- Largest extents first - recover more free space during fixed maintenance windows
- Works with btrfs compression - dedupe any combination of compressed and uncompressed files
- Whole-filesystem dedupe - scans data only once, even with snapshots and reflinks
- Persistent hash table for rapid restart after shutdown
- Constant hash table size - no increased RAM usage if data set becomes larger
- Works on live data - no scheduled downtime required
- Automatic self-throttling - reduces system load
- btrfs support - recovers more free space from btrfs than naive dedupers
Weaknesses
- Whole-filesystem dedupe - has no include/exclude filters, does not accept file lists
- Requires root privilege (
CAP_SYS_ADMINplus the usual filesystem read/modify caps) - 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 for old kernels
- 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 2015-2025 Zygo Blaxell bees@furryterror.org.
GPL (version 3 or later).