btrfs has a problem with it's image as being unreliable (some well deserved). Redhat obsoleted it, because they use kernel 3.10 in RHEL7 and they were doing nothing but backporting, without having any btrfs expertise in house anyway. Btrfs continues to be developed by Oracle, Suse, Facebook, Fujitsu and the rest of the usual suspects.

RHEL is famous for using kernels that are ancient, even by the notoriously conservative and risk averse debian-stable standards.

I can't even imagine the hassle of backporting stuff from much newer kernels into 3.10 to make btrfs work.

If you want to use btrfs in production (not the best idea, IMHO, but orgs such as facebook do it) you absolutely need to be running a 4.9.x or better kernel.

Calling them ancient is a bit unfair, they regularly backport hardware support and select other features from newer kernels. Unlike other distributions, however, they have a stable kernel ABI for an entire release, so they can’t bring in changes that break white listed symbols.

The reason why its not taken off is that its much younger than ZFS, and more crucially its got terrible admin tools and documentation.

It might be a brilliant file system, but I'm never going ot use it because its such an arse to learn how to use it properly.

The Oracle Linux SAG is a reasonable place to start for documentation on it:

https://docs.oracle.com/cd/E52668_01/E54669/html/ol7-about-b...

However, I often end up at the Arch Linux wiki, too:

https://wiki.archlinux.org/index.php/btrfs

Not that I've seen. It's there and works. I think a lot of that impression is driven by the fact that... let's be honest: filesystem features are stale, dinosaur stuff. All the cool kids are worrying about cloud scale storage backends.

At the end of the day btrfs and ZFS both are just ways to help single-system administrators do better and more reliable backups. I know that's not how they're positioned, but really that's all they do.

btrfs still has a lot of issues unfortunately. I tried using buildroot once and the entire filesystem kinda died with the infamous "out of space" error even though there was plenty free. Several RAID levels are also unsafe to use. After experiencing both, I trust ZFS a lot more.

I've only used BTRFS a handful of times and I've still had three filesystems die on me. Two became cripplingly slow, probably because of automatic snapshots (even though there was a small retention limit). One was fine until it suddenly got into a state where it can only be mounted read-only or mounting never finishes, despite a lot of parameters thrown at it trying to fix that. The first two were not terribly long ago, and the last one was 2018.

I had the same experience with btrfs. It killed my machine multiple times.

ZFS on my laptop took me an evening to setup, but it's been completely hassle free. ZFS is really easy to use.

Agreed. However, Synology uses it in their NAS products along with md RAID. Also, SuSE ships it in all their products. OpenSuSE LEAP 15 which was released two weeks ago and has a transactional updates feature that uses btrfs snapshots.

Honestly, I've never really understood the appeal of trying to shoehorn RAID into the FS itself. A more traditional softraid has always felt "good enough" to me (especially in this day and age of affordable SSDs).

ZFS in particular seems to push more toward RAIDZ, whereas I'm a bit averse to striping in general nowadays for data recovery/reliability reasons (RAID1 + JBOD is dead-simple to recover, more flexible with heterogeneous disk sizes, and much easier to reason about IMO).

Not sure where you are getting the push from to use RAIDZ over mirroring. Definitely not from ZFS proper. It's all about what's the best for the situation. Most my things are ZFS mirrors. But given a choice between RAID 3/5/6 or RAIDZ, I don't have to think long.

I've had the opposite experience. I've been using btrfs for years with no issues (pro-tip: don't create 10,000 snapshots and then try to rebalance the fs)

Having snapshots has saved me occasionally and find-new is really useful.

Maybe, but with btrfs your data is definitely at risk. Don't ever use it for anything important. Backups are important but even with those, btrfs is a filesystem that should be uninvented.

It's installed an works many places so it's not quite Hurd.