ZFS State of ZFS xattr support in FreeBSD

I'm trying to work out whether or not, or rather to what extend, xattrs are supported in FreeBSD using ZFS. I've read some conflicting information.
  1. zfs get xattr lists it as on (default) for /, /usr and /var, but as off (temporary) for all other datasets, including children of those mentioned above.
  2. Running zfs set xattr=on zroot/usr/home I get the message
    “property 'xattr' not supported on FreeBSD: permission denied.”
  3. This agrees with the zfs man page:
    “The xattr property is currently not supported on FreeBSD.”
  4. setextattr, getextattr and lsextattr seem to work well enough.
  5. I also managed to save and restore a device file node using rsync --fake-super, and could see its data using lsextattr and getextattr.
  6. Wikipedia has some discussion in the xattr talk page. Apparently there once was a claim that ZFS supports xattr since FreeBSD 8, but that was removed later on, with reference to the manpage (see 3.).
Currently I get the impression that extended attributes on zfs work in practice, but that the xattr property which would control their use does not work as it would in other zfs distributions. But I'd like to hear that confirmed (or corrected) before I trust large amounts of backup data to an rsync --fake-super running on such a machine. I'd rather not lose all my metadata due to known xattr problems.

If it matters, this is a very fresh FreeBSD 10.2 install I just set up, with ZFS set up by the installer.

This is a re-post on a question I previously posted on the Unix & Linux Stack Exchange. So far there was no answer, so I hope for someone more knowledgeable here. If you have an account there as well, feel free to offer an answer there in addition to a reply here.
If you don't get the response that you want here or on Stack Exchange you might want to post your question to the bsdnow.tv podcast. They accept questions and then answer them on the show. There's usually at least one question about ZFS every week. This is probably because Allan Jude (one of the show's hosts) is a ZFS expert. He wrote the ZFS chapter in the handbook and a couple of books on ZFS with Michael Lucas. If you're quick you might even get your question answered on this weeks show.

Alternatively, you could try asking the question on the FreeBSD filesystems mailing list at https://docs.freebsd.org/mail/current/freebsd-fs.html

  • Thanks
Reactions: MvG
I'm not much into podcasts, so the mailing list seemed like the better alternative at the moment. Posted there and waiting for answer(s).