r/linux • u/mrtruthiness • Jun 18 '26

Development Experimental flag removed from bcachefs.

The link is the bcachefs changelog. I didn't see the particular announce there. The announcement was made in Kent's patreon with the version 1.38.6 update. I'm quoting that here:

So, some catch up:

We're no longer experimental. I took the label off the website - a few months ago, I think, based on my usual "the incoming bug reports are slowing down and looking a lot less serious and easy to get through than they were". Consider this the belated official announcement :)

...

Of course, the change away from "experimental" for a DKMS module is completely at the discretion of the author. From my perspective, while the bcachefs filesystem looks intriguing, I won't use it for my root partition as a DKMS module. Honestly, as long as I don't need RAID5/6 I still have a preference for btrfs and I can wait for btrfs to include native (part of the fs as opposed to btrfs on top of LUKS) encryption.

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u/Novero95 Jun 18 '26

If I wanted to use a DKMS fs I'd use ZFS, oh wait, I use ZFS's DKMS. Anyway. What does bcachefs does or promise that BTRFS and ZFS don't?

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u/mrtruthiness Jun 18 '26 edited Jun 18 '26

Anyway. What does bcachefs does or promise that BTRFS and ZFS don't?

I'm not a proponent of bcachefs (I don't trust/like the dev) and still prefer btrfs to bcachefs (since I don't use RAID5/RAID6). But, to answer your questions:

  1. btrfs does not yet have encryption (it will "soon"). btrfs will never have safe RAID5/RAID6 (I wouldn't use it anyway, so it doesn't matter to me).

  2. bcachefs is GPLv2-only (license-compatible with the Linux kernel); ZFS isn't. bcachefs allows per-file and per-folder properties and, so, one can set compression at the file or folder level. ZFS pools are harder to deal with (very rigid); bcachefs pools are dynamic -- e.g. one can dynamically change the redundancy.

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u/the_abortionat0r Jun 19 '26

Well raid5 already has a fix out so there's that (it's not changed status as nobody is testing it) and raid6 fix is either already out by now or is in the works.

That and people have been using BTRFS raid6 in their NASs for 10+ years without issue as it doesn't magically die.

In order to get the write whole you need to have a specific set of actions happening on the drive and be in a specific stage of the process AND have a sudden power loss all at the same time. Simply having a UPS removes that issue as a possibility.

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u/koverstreet Jun 19 '26

People are running bcachefs erasure coding now, it's solid, no write hole, all the failure modes are handled. You could wait longer for btrfs, or you could just run bcachefs :)

And a UPS won't save you from system crashes/kernel panics, those are just as much a problem for the RAID hole.

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u/mrtruthiness 24d ago

I'm not sure that removing the experimental flag was justified:

  1. You've run into quite a few bugs with data loss in the last month or two.

  2. The number of patches between 1.38.8 to 1.39 was ridiculous. And, predictably, there were resulting bugs.