Natalie Spiva — Lead Infrastructure Architect Darren Clift — Co-Lead Developer
We built YAcFS because the existing filesystem landscape is broken.
ZFS is trapped behind a CDDL licensing wall that makes it impossible to ship as part of the Linux kernel. Every distro that wants ZFS has to jump through hoops — DKMS, out-of-tree modules, license incompatibility fights. It's 2026 and we're still dealing with this. ZFS is also a memory hog, requires tuning to run well on commodity hardware, and its RAID-Z expansion is still painful.
btrfs was supposed to be the answer. It's in the kernel, it's GPL, it has all the features. But after a decade and a half, it still has edge cases that eat your data — the RAID56 code is still considered dangerous, send/receive can produce corrupted streams under load, and performance on spinning rust is genuinely bad. We've lost data to btrfs. We're done trusting it.
Everything else (ext4, XFS) is a journaling filesystem from the 90s. No checksums. No snapshots. No compression. No self-healing. In 2026, storing data without integrity verification is irresponsible.
So we wrote YAcFS — Yet Another common File System — the filesystem that should have existed all along.
YAcFS is:
- GPLv3 — No licensing bullshit. Ships in every kernel. Every distro.
- Fast — Writeback cache, kernel page cache, block-level content dedup, xxhash3 checksums, ZSTD compression tuned for speed.
- Simple — One binary, one pool directory. Mount it and go.
- Safe — Checksums on every read. Content-addressable blocks. COW snapshots.
- Pooled — Union multiple directories into one filesystem pool.
We built it because we were tired of choosing between "works with Linux" and "has basic data integrity features." YAcFS gives you both — and outperforms both ZFS and btrfs on real-world workloads.
Built by AcreetionOS — for everyone.
Full documentation is available under docs/yacfs/:
| Document | Description |
|---|---|
| Overview | What YAcFS is and its key features |
| Architecture | On-disk format, block store, metadata, caching |
| Usage | Installation, mounting, snapshots, pooling |
| Performance | Benchmarks vs ZFS, btrfs, ext4 |
| API | Developer documentation, FUSE ops reference |
| Contributing | How to contribute to YAcFS |
"99.9% uptime — not just in the systems I build, but in my own survival and evolution." — Natalie Spiva