>Is there anything FreeBSD can do that, say, Debian cannot?
ZFS boot environments.
One could install Debian's root on ZFS by following the OpenZFS documentation guide, combine it with ZFSBootMenu (or similar), but there won't be any upstream support from the Debian project itself.
The Nitrux Linux distribution is based on Debian and provides an immutable feature similar to boot environments, but you can't treat your immutable boot images the same way you can treat your mutable data like how you can with ZFS datasets on FreeBSD.
you can use snapper + btrfs and the end result is like `bectl`. However it not as simple/integrated as ZFS Boot environments on FreeBSD
On openSUSE Tumbleweed, it is. Each Upgrade creates two snapshots, one before, one after, and if anything goes wrong, I can boot into a snapshot where the world was still in order.
I have a higher opinion of ZFS than I do of btrfs, but FWIW snapper+btrfs has worked well for me on openSUSE Tumbleweed for ten years now, too.
The btrfs code quality seems less than ZFS, based on the reports I have read.
Last I heard (~8 years ago), the RAID-like functionality in btrfs was very unstable and crash-prone. The impression I got was that there was not a lot of interest in fixing this. Then bcachefs came and ... appears to have gone nowhere AFAICT.
The non-RAID part of btrfs appears to be stable. It's the default filesystem on openSUSE and SLES. But I don't think it's ever going to reach feature parity with ZFS.
btrfs is suffering from a lot of old bad publicity and some poor design decisions around RAID.
But by now it is a great file system if you don't go near RAID5/6. btrfs has its flaws (ZFS has its own flaws!). However:
- It's used a lot, especially by facebook and Redhat (on fedora)
- Gets a lot of testing
- Sees a lot of bug fixes
- Has a lot of features
I haven't read btrfs code but given that it is a popular file system and Linux code quality tends to be good in popular subsystems I would hesitate to say its code quality is worse than ZFS in any way.
btrfs is pathetic when it comes to performance. So no, thanks.
https://www.phoronix.com/review/linux-70-filesystems
In real world scenarios, where file based backups fail, one needs to add at least lvm.
And only than those benchmarks would be more interesting to me.