mirror of
https://github.com/Zygo/bees.git
synced 2025-05-17 13:25:45 +02:00
14ce81c081
The base class thing was an ugly way to get around the lack of C99 compound literals in C++, and also to make the bare ioctls usable with the derived classes. Today, both clang and gcc have C99 compound literals, so there's no need to do crazy things with memset. We never used the derived classes for ioctls, and for this specific ioctl it would have been a very, very bad idea, so there's no need to support that either. We do need to jump through hoops for ostream& operator<<() but we had to do those anyway as there are other members in the derived type. So we can simply drop the base class, and build the args object on the stack in `do_ioctl`. This also removes the need to verify initialization. There's no bug here since the `info` member of the base class was never used in place by the derived class, but new compilers reject the flexible array member in the base class because the derived class makes `info` be not at the end of the struct any more: error: flexible array member btrfs_ioctl_same_args::info not at end of struct crucible::BtrfsExtentSame Fixes: https://github.com/Zygo/bees/issues/232 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 snapshots - 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 2015-2022 Zygo Blaxell bees@furryterror.org.
GPL (version 3 or later).