After 17 years of existance one would assume they have fixed all major flaws. Anyone knows why raid is still broken on btrfs? And what is the next fs after zfs and btrfs? There should be a major contender by now, but I see none.
I believe the recommendation is to run btrfs on top of mdraid, which works fine. Meta is said to use btrfs, but apparently they don't care about the raid implementation, so there's nobody paying for that development.
OpenZFS works fine, but it can be tricky to install due to the license thing, not all distributions support it in their installer.
Bcachefs is said to be the up and coming contender for both, but it was merged to the mainline kernel in January, so probably at the moment it is tricky to install as well. I would think many of this year's distribution releases will make it available.
IMO the "next fs" is just zfs. They somewhat recently merged RAIDZ expansion feature https://github.com/openzfs/zfs/pull/12225 and make regular improvements. If no file system has what you need today, zfs will probably be the first one to have it "tomorrow," imo.
For all the talk about the raid5/6 issues on btrfs, people don't seem motivated enough to actually spend time fixing this. It's almost as if mdadm was enough and there wasn't that much drive to make it happen.
