Selfhosted

btrfs has been the default file system for Fedora Workstation since Fedora 33 so not much reason to not use it.

Didn't have any btrfs problems yet, infact cow saved me a few times on my desktop.

Don't use btrfs if you need RAID 5 or 6.

The RAID56 feature provides striping and parity over several devices, same as the traditional RAID5/6. There are some implementation and design deficiencies that make it unreliable for some corner cases and the feature should not be used in production, only for evaluation or testing. The power failure safety for metadata with RAID56 is not 100%.

https://btrfs.readthedocs.io/en/latest/btrfs-man5.html#raid56-status-and-recommended-practices

Btrfs came default with my new Synology, where I have it in Synology's raid config (similar to raid 1 I think) and I haven't had any problems.

I don't recommend the btrfs drivers for windows 10. I had a drive using this and it would often become unreachable under load, but this is more a Windows problem than a problem with btrfs

A bit of topic; am I the only one that pronounces it "butterface"?

You shouldn't have abysmal performance with ZFS. Something must be up.

No reason not to. Old reputations die hard, but it's been many many years since I've had an issue.

I like also that btrfs is a lot more flexible than ZFS which is pretty strict about the size and number of disks, whereas you can upgrade a btrfs array ad hoc.

I'll add to avoid RAID5/6 as that is still not considered safe, but you mentioned RAID1 which has no issues.

Did you set the correct block size for your disk? Especially modern SSDs like to pretend they have 512B sectors for some compatibility reason, while the hardware can only do 4k sectors. Make sure to set ashift=12.

Proxmox also uses a very small volblocksize by default. This mostly applies to RAIDz, but try using a higher value like 64k. (Default on Proxmox is 8k or 16k on newer versions)

https://discourse.practicalzfs.com/t/psa-raidz2-proxmox-efficiency-performance/1694

What kind of disks, and how is your ZFS set up? Something seems amis here.

For my jbod array, I use ext4 on gpt partitions. Fast efficient mature.

For anything else I use ext4 on lvm thinpools.

I've been using single-disk btrfs for my rootfs on every system for almost a decade. Great for snapshots while still being an in-tree driver. I also like being able to use subvolumes to treat / and /home (maybe others) similar to separate filesystems without actually being different partitions.

I had used it for my NAS array too, with btrfs raid1 (on top of luks), but migrated that over to ZFS a couple years ago because I wanted to get more usable storage space for the same money. btrfs raid5 is widely reported to be flawed and seemed to be in purgatory of never being fixed, so I moved to raidz1 instead.

One thing I miss is heterogenous arrays: with btrfs I can gradually upgrade my storage one disk at a time (without rewriting the filesystem) and it uses all of my space. For example, two 12TB drives, two 8TB drives, and one 4TB drive adds up to 44TB and raid1 cuts that in half to 22TB effective space. ZFS doesn't do that. Before I could migrate to ZFS I had to commit to buying a bunch of new drives (5x12TB not counting the backup array) so that every drive is the same size and I felt confident it would be enough space to last me a long time since growing it after the fact is a burden.

My setup is different to yours but not totally different. I run ESXi 8, and I started to use BTRFS on some of my VM's.

I had a power failure, that was longer than the UPS could handle. Most of the system shutdown safely, a few VM's did not. All of the EXT4 VM's were easily recovered (including another one that was XFS). TWO of the BTRFS systems crashed into a non recoverable state.

Nothing I could do to fix them, they were just toast. I had no choice but to recover using backups. This made me highly aware that BTRFS is still not a reliable FS.

I am migrating everything from BTRFS to something more stable and reliable like EXT4. It's simply not worth the headache.