Remove of dataset not possible

TrueNAS General
1

Hi,
I created a dataset from a snapshot in the same pool as the snapshot is from.

Mainpool/… ← one snapshot of all datasets

Now I can’t delete the “snapshot”-dataset

root@truenas[~]# zfs list | grep Mainpool
Mainpool                                                   3.35T  8.95T   160K  /mnt/Mainpool
Mainpool/.system                                           1.94G  8.95T  1.47G  legacy
Mainpool/.system/configs-ae32c386e13840b2bf9c0083275e7941  25.5M  8.95T  25.5M  legacy
Mainpool/.system/cores                                      128K  1024M   128K  legacy
Mainpool/.system/netdata-ae32c386e13840b2bf9c0083275e7941   460M  8.95T   460M  legacy
Mainpool/.system/nfs                                        149K  8.95T   149K  legacy
Mainpool/.system/samba4                                     368K  8.95T   368K  legacy
Mainpool/Bilder                                             378G   646G   378G  /mnt/Mainpool/Bilder
Mainpool/Data                                              2.86T  8.95T  2.86T  /mnt/Mainpool/Data
Mainpool/Musik                                              114G  86.2G   114G  /mnt/Mainpool/Musik
Mainpool/ix-applications                                   1.10G   255G   186K  /mnt/Mainpool/ix-applications
Mainpool/ix-applications/catalogs                          77.0M   255G  77.0M  /mnt/Mainpool/ix-applications/catalogs
Mainpool/ix-applications/default_volumes                    128K   255G   128K  /mnt/Mainpool/ix-applications/default_volumes
Mainpool/ix-applications/k3s                               1.03G   255G  1.02G  /mnt/Mainpool/ix-applications/k3s
Mainpool/ix-applications/k3s/kubelet                        485K   255G   485K  legacy
Mainpool/ix-applications/releases                           128K   255G   128K  /mnt/Mainpool/ix-applications/releases
Mainpool/ix-apps                                            183M  8.95T   149K  /mnt/.ix-apps
Mainpool/ix-apps/app_configs                                128K  8.95T   128K  /mnt/.ix-apps/app_configs
Mainpool/ix-apps/app_mounts                                 128K  8.95T   128K  /mnt/.ix-apps/app_mounts
Mainpool/ix-apps/docker                                    1.04M  8.95T  1.04M  /mnt/.ix-apps/docker
Mainpool/ix-apps/truenas_catalog                            182M  8.95T   182M  /mnt/.ix-apps/truenas_catalog
Mainpool/manual-2025-04-10_17-58-clone                      149K  8.95T   149K  /mnt/Mainpool/manual-2025-04-10_17-58-clone

root@truenas[~]# zfs destroy Mainpool/manual-2025-04-10_17-58-clone
cannot destroy 'Mainpool/manual-2025-04-10_17-58-clone': filesystem has children
use '-r' to destroy the following datasets:
Mainpool/manual-2025-04-10_17-58-clone@manual-2025-04-10_17-58

root@truenas[~]# zfs destroy -r Mainpool/manual-2025-04-10_17-58-clone@manual-2025-04-10_17-58
cannot destroy 'Mainpool/manual-2025-04-10_17-58-clone@manual-2025-04-10_17-58': snapshot has dependent clones
use '-R' to destroy the following datasets:
Mainpool/manual-2025-04-10_17-58-clone@manual-2025-04-10_17-58
Mainpool/manual-2025-04-10_17-58-clone
Mainpool/Musik
Mainpool/Bilder
Mainpool/Data
Mainpool/.system/netdata-ae32c386e13840b2bf9c0083275e7941
Mainpool/.system/samba4
Mainpool/.system/cores
Mainpool/.system/nfs
Mainpool/.system/configs-ae32c386e13840b2bf9c0083275e7941
Mainpool/.system
Mainpool/ix-apps/app_mounts
Mainpool/ix-apps/app_configs
Mainpool/ix-apps/docker
Mainpool/ix-apps/truenas_catalog
Mainpool/ix-apps
Mainpool/ix-applications/releases
Mainpool/ix-applications/catalogs
Mainpool/ix-applications/k3s/kubelet
Mainpool/ix-applications/k3s
Mainpool/ix-applications/default_volumes
Mainpool/ix-applications
Mainpool
root@truenas[~]#

How can I delete the dataset?

2

What were you trying to accomplish in the first place?

Did you intentionally want to make a clone (“dataset birthed from a snapshot”)?

Then you made a snapshot for the cloned dataset, which is why -r is needed to destroy the clone (dataset).

Before you do anything destructive, please make a checkpoint for your pool:

zpool checkpoint Mainpool
zpool get checkpoint Mainpool
zpool status Mainpool | grep checkpoint

Once you confirm there’s a checkpoint, do a “dry run” destruction (using the -n flag) of the cloned dataset and its snapshot(s). Paste the output of what it would have destroyed:

zfs destroy -nvr Mainpool/manual-2025-04-10_17-58-clone
1 Like
3 
root@truenas[~]# zpool checkpoint Mainpool
root@truenas[~]# zpool get checkpoint Mainpool
NAME      PROPERTY    VALUE    SOURCE
Mainpool  checkpoint  1.12M    -
root@truenas[~]# zpool status Mainpool | grep Mainpool
  pool: Mainpool
        Mainpool                                  ONLINE       0     0     0
root@truenas[~]# zfs destroy -nvr Mainpool/manual-2025-04-10_17-58-clone
cannot destroy 'Mainpool/manual-2025-04-10_17-58-clone': filesystem has dependent clones
use '-R' to destroy the following datasets:
Mainpool/Musik
Mainpool/Bilder
Mainpool/Data
Mainpool/.system/netdata-ae32c386e13840b2bf9c0083275e7941
Mainpool/.system/samba4
Mainpool/.system/cores
Mainpool/.system/nfs
Mainpool/.system/configs-ae32c386e13840b2bf9c0083275e7941
Mainpool/.system
Mainpool/ix-apps/app_mounts
Mainpool/ix-apps/app_configs
Mainpool/ix-apps/docker
Mainpool/ix-apps/truenas_catalog
Mainpool/ix-apps
Mainpool/ix-applications/releases
Mainpool/ix-applications/catalogs
Mainpool/ix-applications/k3s/kubelet
Mainpool/ix-applications/k3s
Mainpool/ix-applications/default_volumes
Mainpool/ix-applications
Mainpool
root@truenas[~]#
4

I’m not exactly sure what you did or tried to do. It’s like some crazy infinite loop of the pool’s root dataset somehow being dependent on a cloned dataset?

What does this show?

zpool history Mainpool | grep clone
5 
root@truenas[~]# zpool history Mainpool | grep clone
2025-04-10.17:59:11 py-libzfs: zfs clone Mainpool@manual-2025-04-10_17-58
2025-04-10.17:59:19 py-libzfs: zfs promote Mainpool/manual-2025-04-10_17-58-clone
root@truenas[~]#
6
  • created a manual snapshot of Mainpool
  • cloned the snapshot into the Mainpool
  • promoted the cloned snapshot to see the content
7

You didn’t need to do that…

You can navigate the contents of ZFS snapshots, as it is.

There’s no need to clone a snapshot into a new dataset or promote this cloned dataset.

1 Like
8

What does this show?

zfs get -t filesystem,volume -r origin Mainpool | grep "@"
9 
root@truenas[~]# zfs get -t filesystem,volume -r origin Mainpool | grep "@"
Mainpool                                                   origin    Mainpool/manual-2025-04-10_17-58-clone@manual-2025-04-10_17-58  -
root@truenas[~]#
10

You have a snake eating its own tail.

This should hopefully reverse what you did.

zfs promote Mainpool

Not sure if this will explode your server.

2 Likes
11 
root@truenas[~]# zfs promote Mainpool
root@truenas[~]# zfs get -t filesystem,volume -r origin Mainpool 
NAME                                                       PROPERTY  VALUE                             SOURCE
Mainpool                                                   origin    -                                 -
Mainpool/.system                                           origin    -                                 -
Mainpool/.system/configs-ae32c386e13840b2bf9c0083275e7941  origin    -                                 -
Mainpool/.system/cores                                     origin    -                                 -
Mainpool/.system/netdata-ae32c386e13840b2bf9c0083275e7941  origin    -                                 -
Mainpool/.system/nfs                                       origin    -                                 -
Mainpool/.system/samba4                                    origin    -                                 -
Mainpool/Bilder                                            origin    -                                 -
Mainpool/Data                                              origin    -                                 -
Mainpool/Musik                                             origin    -                                 -
Mainpool/ix-applications                                   origin    -                                 -
Mainpool/ix-applications/catalogs                          origin    -                                 -
Mainpool/ix-applications/default_volumes                   origin    -                                 -
Mainpool/ix-applications/k3s                               origin    -                                 -
Mainpool/ix-applications/k3s/kubelet                       origin    -                                 -
Mainpool/ix-applications/releases                          origin    -                                 -
Mainpool/ix-apps                                           origin    -                                 -
Mainpool/ix-apps/app_configs                               origin    -                                 -
Mainpool/ix-apps/app_mounts                                origin    -                                 -
Mainpool/ix-apps/docker                                    origin    -                                 -
Mainpool/ix-apps/truenas_catalog                           origin    -                                 -
Mainpool/manual-2025-04-10_17-58-clone                     origin    Mainpool@manual-2025-04-10_17-58  -
root@truenas[~]# 
root@truenas[~]#
12

Looks good.

Now we can try this again:

zfs destroy -nvr Mainpool/manual-2025-04-10_17-58-clone
1 Like
13

Deletion of the dataset has worked now - Thanks!

1 Like
14

Please be careful going forward.

Next time ask about something before you experiment with commands outside of the GUI.

You would have learned that the contents of a ZFS snapshot are browsable, without the need to clone or promote anything.

If you feel safe at this point, you can discard the pool checkpoint.

zpool checkpoint -d Mainpool
zpool get checkpoint Mainpool

The second command should result with a - under the “VALUE” column, as no checkpoint exists now.

I’m assuming you actually deleted the dataset (clone) without the “dry run”?

15

The checkpoint is removed.
And the destroyed the clone by using the command without the n parameter.

16

Be honest with me. Was it ChatGPT? Did you get the idea to do what you did from an AI chatbot? :wink:

It’s okay. I won’t judge you.

1 Like
17

I saw a youtube video explaining to show the content of an snapshot in TrueNAS by cloning and promoting. Both is possible using the web-ui.
Video

18

Starting from the 11:00 mark until 12:50, I think it’s a bit too much just to browse or recover files from a snapshot.

Without cloning, you can do the following:

  • In the command-line, navigate to /mnt/<pool>/<dataset>/.zfs/snapshot/, which will present your read-only snapshots in the form of browsable “folders”.
  • Over a network share (SMB, NFS), you can visit \\<server.address>\<sharename>\.zfs\snapshot\, to browse and copy files from read-only snapshots. This assumes you’re sharing a dataset’s root path, and not some subfolder within a dataset.

No need to clone, and definitely no need to promote anything.

The .zfs folder is hidden, so you must manually type in this directory when using the command-line or a graphical file browser’s address bar.

1 Like
19

Youtube videos (without understanding the things they are telling you) about as bad as chatgpt.