From https://orib.dev/gefs.pdf -

> While snapshot consistency is useful to keep data consistent, disks often fail over time. In order to detect corruption, block pointers contain a hash of the data that they point at. If corrupted data is returned by the underlying storage medium, this is detected via block hashes. And if a programmer error causes the file system to write garbage to disk, this can often be caught early. The corruption is reported, and the damaged data may then be recovered from backups, RAID restoration, or some other means.

Okay! It's got CoW, snapshots, and data checksums. Therefore, it's good enough to compete with ZFS while being way smaller and permissively licensed. Now I just want it ported to Linux and the other BSDs:)

I don't think it will compete with ZFS or BTRFS (e.g. I don't think ppl will use GEFS over ZFS or BTRFS for a storage server), but it's a modern, much needed FFS replacement.

There was a recent presentation on this at EuroBSDCon for those interested.

https://events.eurobsdcon.org/2026/talk/NVMSCJ/

https://exquisite.tube/w/3QQimMdswWJxrsPaJtak2u

Is there any chance of proving a filesystem is correct?

Is this one simple enough that it won’t have bugs??

Given the issues with well-known filesystems like ZFS and BetterFS, why shouldn’t I expect data-losing bugs in this one?

I think the premise is basically yes, you should assume there will be data-losing bugs, but:

1. The filesystem should be reasonably good at detecting an error/corruption state and informing you, and

2. You should have backups of said data stored elsewhere, and backups should be tested (e.g. to verify that data can be read back)

What well known data-losing bugs are there in zfs? It can be slow, and resource hungry, but afaik it's about as safe as they come (and I've been using it in prod since solaris 10)

I never dug into the failure, but I once had a ZFS get to a state where it would crash the kernel on mount, I was able to mount it with checks turned off an recover what was important, but it was a spooky experience. I live on the bleeding edge of file systems for my desktop, I was on reiser4 back when that was fresh, I daily drive bcachefs (it's been great!) Mostly I've been lucky, I don't usually keep an openbsd system around, but I love FreeBSD and I'll give OpenBSD a try with GEFS for sure!

There was a long-running data corruption issue with non-raw sends that was finally found and patched in 2025: https://github.com/openzfs/openzfs-docs/issues/494. But I agree, it's about as safe as they come. I trust it far more than any other file system, in large part due to all its built-in redundancy and the way it makes backups trivial (encrypted sends <3)...

I've been following (and helping test) gefs on 9front for a while now. 9front's nightly builder has been running off of it for quite a while. Ori's done a fantastic job.

Talk at EuroBSDCon 2026: https://exquisite.tube/w/3QQimMdswWJxrsPaJtak2u

GEFS: A Good Enough File System https://orib.dev/gefs.pdf

> The git repo is hidden on shithub

Heh :)

This is great timing considering I'm currently dealing with FFS corruption after my OpenBSD server lost power during a storm.

Finally . Very good work team !

Ori B. it's a great programmer, he fixed a small bug on the earlier GeFS on 9front versions in no time. It worked fine in my n270 based Atom netbook under 9front, so it will run perfectly well under OpenBSD in a near future.

It isn't as resource heavy as ZFS, and it will be more reliable than FFS, for sure.