mirror of
https://github.com/Zygo/bees.git
synced 2025-05-17 21:35:45 +02:00
8bac00433d
Originally the limit was 2730 (64KiB worth of ref pointers). This limit was a little too low for some common workloads, so it was then raised by a factor of 256 to 699050, but there are a lot of problems with extent counts that large. Most of those problems are memory usage and speed problems, but some of them trigger subtle kernel MM issues. 699050 references is too many to be practical. Set the limit to 9999, only 3-4x larger than the original 2730, to give up on deduplication when each deduped ref reduces the amount of space by no more than 0.01%. 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
- 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 2015-2023 Zygo Blaxell bees@furryterror.org.
GPL (version 3 or later).