3 ms·

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

by fn-mote 19d ago

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?

spijdar 19d ago
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)
cyberpunk 19d ago
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)
- alethic 19d ago
  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 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)...
- sellmesoap 19d ago
  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!
- yjftsjthsd-h 19d ago
  Its native encryption has something of a poor history

3 ms·

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

by fn-mote 19d ago

spijdar 19d ago
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)
cyberpunk 19d ago
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)
- alethic 19d ago
  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 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)...
- sellmesoap 19d ago
  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!
- yjftsjthsd-h 19d ago
  Its native encryption has something of a poor history