zfs has a feature where you can `cd` to hidden .zfs folder (you wont see it by `ls`, imagine it like /procfs but hidden) on root of zfs filesystem (if you have tank/whatever mounted to /whatever this would be /whatever/.zfs) with some interesting content: within .zfs/snapshot you will get a list of snapshots for that filesystem with materialized state (!!!) of fs when the snapshot was taken. Imagine (instead of rollback the snapshot), just copying the original file(s) from there, with content from the time when snapshot was created.

This is imho, the killer feature of zfs, maybe matching only by VMS or DragonflyBSD hammer filesystems. They were/are both better at it (`undo`!) but zfs comes closely.

And it is broken for months now.

> And it is broken for months now.

This guy speaks without knowing.

I just tried going in my .zfs/snapshot on my CentOS 7 system running kernel 3.10 and ZoL 0.8.3 and it's working. I can list snapshots and cat file off a snapshot.

> CentOS 7 system running kernel 3.10

what the actual f*?

  tag name v3.10 (bc1b510b8979ecc322f8d930dde56658967b7355)
  tag date 2013-06-30 15:13:42 -0700

Even with stable fixes and CentOS distro sugar on top, running 3.10.x in 2020 feels batshit crazy. I always thought such reptilian kernels are only found on shitty embedded devices...

RHEL kernels are like that. They backport a ton of stuff and the major version number is of little relevance, but it doesn't change because they maintain a stable kABI.

By now the CentOS 7 kernel is probably closer to mainline 4.x and 5.x than the original 3.10

Wait until you find 2.6 (not many changes before 3.2 allegedly) and 2.4 kernels in embedded systems.

I'm well aware of 2.6 in embedded systems (and have to work with such systems T_T), I just didn't expect to see 3.10 in a system that also runs ZFS...

After 10+ years of using zfs, I just "might" know something... ;) While your 1 year old versions of ZoL just "might" not prove anything.

if you had actually been using it during the last 1.5/2 years you would know it work.

otherwise you're just talking about stuff (zfs on gnu/linux) you know little about.

if you use zfs on freebsd then good for you, but that doesn't mean you can spread disinformation about zfs-on-linux.

btw: freebsd dropped its own implementation of zfs and is rebasing onto zfs-on-linux (from 2018: https://lists.freebsd.org/pipermail/freebsd-fs/2018-December...). that's how good zfs-on-linux is.

Just update your outdated ZoL to latest version. Than we can talk. And you might just agree.

I run ZFS on both Linux and FreeBSD. On Linux I compile from the latest releases. I’ve honestly not noticed any issues either.

Are you absolutely sure this isn’t something you’ve misconfigured yourself?

For what it’s worth, I do prefer FreeBSD over Linux but not not for any reasons relating to ZFS.

  $ cat /saspool/debian/master-buster/.zfs/snapshot/ci/etc/issue     
  Debian GNU/Linux 10 \n \l

ZFS 0.8.4 on Linux 5.4.43 — just as a data point in case you're trying to track this down. Both built from source, no distro patches.

(Yes my "tank" is named "pool"; /saspool/debian/master-buster is a template for my containers, "ci" is one of the containers.)

Works for me on Debian Unstable...

   sudo zpool --version
   zfs-0.8.4-1
   zfs-kmod-0.8.4-1

   uname -a
   Linux xxx 5.6.0-2-amd64 #1 SMP Debian 5.6.14-1 (2020-05-23) x86_64 GNU/Linux

I haven't noticed that issue on Proxmox (been using zfs with it for approx. 6 months). Currently on zfs 0.8.4 (and I've done that previously).

Are you using a distro supplied zfs (potentially old) or rolling something more bleeding edge?

Just for any case, I would really love to solve this, I accept the fact that it is connected with upgrading the modules but this just is no reason for breaking backward compatibility.

root> zpool --version

zfs-0.8.4-1

zfs-kmod-0.8.4-1

root> ll /.zfs/snapshot

total 0

drwxrwxrwx 2 root root 2 jun 15 08:48 ./

drwxrwxrwx 1 root root 0 jun 10 07:53 ../

root> cat /etc/yum.repos.d/zfs.repo

[zfs]

name=ZFS on Linux for Fedora $releasever

baseurl=http://download.zfsonlinux.org/fedora/$releasever /$basearch/

enabled=1

metadata_expire=7d

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-zfsonlinux

[zfs-source]

name=ZFS on Linux for Fedora $releasever - Source baseurl=http://download.zfsonlinux.org/fedora/$releasever/SRPMS/

enabled=0

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-zfsonlinux

But nevermind, this is something that was working since zfs as root was brought into FreeBSD (and we are talking about FreeBSD not ZoL), never had issues about it.