I have tried this fix from another thread:
First I made a checkpoint according to the walkthrough (better safe than sorry!)
truenas_admin@truenas[~]$ sudo zpool get checkpoint Pool_0
NAME PROPERTY VALUE SOURCE
Pool_0 checkpoint - -
truenas_admin@truenas[~]$ sudo zpool checkpoint Pool_0
truenas_admin@truenas[~]$ sudo zpool status Pool_0 | grep checkpoint
checkpoint: created Wed Jun 25 22:28:57 2025, consumes 1.38M
After unmounting (un-forceful), “zfs inherit -r mountpoint” seemes to work, at least partially.
truenas_admin@truenas[~]$ sudo zfs unmount Pool_0
truenas_admin@truenas[~]$ sudo zfs inherit -r mountpoint Pool_0
cannot unmount '/var/db/system': pool or dataset is busy
cannot unmount '/var/db/system/netdata': pool or dataset is busy
cannot unmount '/var/db/system/samba4': pool or dataset is busy
And “zfs get” looks right to me:
truenas_admin@truenas[~]$ sudo zfs get -t filesystem -r mountpoint Pool_0
NAME PROPERTY VALUE SOURCE
Pool_0 mountpoint /mnt/Pool_0 default
Pool_0/.system mountpoint legacy local
Pool_0/.system/configs-ae32c386e13840b2bf9c0083275e7941 mountpoint legacy inherited from Pool_0/.system
Pool_0/.system/cores mountpoint legacy inherited from Pool_0/.system
Pool_0/.system/netdata-ae32c386e13840b2bf9c0083275e7941 mountpoint legacy local
Pool_0/.system/nfs mountpoint legacy inherited from Pool_0/.system
Pool_0/.system/samba4 mountpoint legacy local
Pool_0/ChenYZ mountpoint /mnt/Pool_0/ChenYZ default
Pool_0/ChenYZ/chenyz mountpoint /mnt/Pool_0/ChenYZ/chenyz default
Pool_0/Download mountpoint /mnt/Pool_0/Download default
Pool_0/Download/chenyz mountpoint /mnt/Pool_0/Download/chenyz default
Pool_0/StableDiffusion_Files mountpoint /mnt/Pool_0/StableDiffusion_Files default
Pool_0/WPS_sync mountpoint /mnt/Pool_0/WPS_sync default
Pool_0/apps mountpoint /mnt/Pool_0/apps default
Pool_0/ix-applications.broken mountpoint /mnt/Pool_0/ix-applications.broken default
Pool_0/ix-applications.broken/catalogs mountpoint /mnt/Pool_0/ix-applications.broken/catalogs default
Pool_0/ix-applications.broken/default_volumes mountpoint /mnt/Pool_0/ix-applications.broken/default_volumes default
Pool_0/ix-applications.broken/k3s mountpoint /mnt/Pool_0/ix-applications.broken/k3s default
Pool_0/ix-applications.broken/k3s/kubelet mountpoint /mnt/Pool_0/ix-applications.broken/k3s/kubelet default
Pool_0/ix-applications.broken/releases mountpoint /mnt/Pool_0/ix-applications.broken/releases default
Pool_0/ix-applications.broken/releases/home-assistant mountpoint /mnt/Pool_0/ix-applications.broken/releases/home-assistant default
Pool_0/ix-applications.broken/releases/home-assistant/charts mountpoint /mnt/Pool_0/ix-applications.broken/releases/home-assistant/charts default
Pool_0/ix-applications.broken/releases/home-assistant/volumes mountpoint /mnt/Pool_0/ix-applications.broken/releases/home-assistant/volumes default
Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes mountpoint /mnt/Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes default
Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes/config mountpoint /mnt/Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes/config default
Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes/media mountpoint /mnt/Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes/media default
Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes/pgBackup mountpoint /mnt/Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes/pgBackup default
Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes/pgData mountpoint /mnt/Pool_0/ix-applications.broken/releases/home-assistant/volumes/ix_volumes/pgData default
Pool_0/ix-applications.broken/releases/qbittorrent mountpoint /mnt/Pool_0/ix-applications.broken/releases/qbittorrent default
Pool_0/ix-applications.broken/releases/qbittorrent/charts mountpoint /mnt/Pool_0/ix-applications.broken/releases/qbittorrent/charts default
Pool_0/ix-applications.broken/releases/qbittorrent/volumes mountpoint /mnt/Pool_0/ix-applications.broken/releases/qbittorrent/volumes default
Pool_0/ix-applications.broken/releases/qbittorrent/volumes/ix_volumes mountpoint /mnt/Pool_0/ix-applications.broken/releases/qbittorrent/volumes/ix_volumes default
Pool_0/ix-applications.broken/releases/qbittorrent/volumes/ix_volumes/config mountpoint /mnt/Pool_0/ix-applications.broken/releases/qbittorrent/volumes/ix_volumes/config default
Pool_0/ix-applications.broken/releases/qbittorrent/volumes/ix_volumes/downloads mountpoint /mnt/Pool_0/ix-applications.broken/releases/qbittorrent/volumes/ix_volumes/downloads default
Pool_0/ix-applications.broken/releases/zerotier mountpoint /mnt/Pool_0/ix-applications.broken/releases/zerotier default
Pool_0/ix-applications.broken/releases/zerotier/charts mountpoint /mnt/Pool_0/ix-applications.broken/releases/zerotier/charts default
Pool_0/ix-applications.broken/releases/zerotier/volumes mountpoint /mnt/Pool_0/ix-applications.broken/releases/zerotier/volumes default
Pool_0/ix-applications.broken/releases/zerotier/volumes/ix_volumes mountpoint /mnt/Pool_0/ix-applications.broken/releases/zerotier/volumes/ix_volumes default
Pool_0/ix-apps mountpoint /mnt/Pool_0/ix-apps default
Pool_0/ix-apps/app_configs mountpoint /mnt/Pool_0/ix-apps/app_configs default
Pool_0/ix-apps/app_mounts mountpoint /mnt/Pool_0/ix-apps/app_mounts default
Pool_0/ix-apps/app_mounts/qbittorrent mountpoint /mnt/Pool_0/ix-apps/app_mounts/qbittorrent default
Pool_0/ix-apps/app_mounts/qbittorrent/config mountpoint /mnt/Pool_0/ix-apps/app_mounts/qbittorrent/config default
Pool_0/ix-apps/app_mounts/qbittorrent/downloads mountpoint /mnt/Pool_0/ix-apps/app_mounts/qbittorrent/downloads default
Pool_0/ix-apps/app_mounts/zerotier mountpoint /mnt/Pool_0/ix-apps/app_mounts/zerotier default
Pool_0/ix-apps/app_mounts/zerotier/config mountpoint /mnt/Pool_0/ix-apps/app_mounts/zerotier/config default
Pool_0/ix-apps/docker mountpoint /mnt/Pool_0/ix-apps/docker default
Pool_0/ix-apps/truenas_catalog mountpoint /mnt/Pool_0/ix-apps/truenas_catalog default
However, as the other thread says exporting the pool via cli and import via gui to make changes permanent and let the middleware know, again i met with dataset busy.
truenas_admin@truenas[~]$ sudo zpool export Pool_0
cannot unmount '/var/db/system/samba4': pool or dataset is busy
The question is, should i forcefully unmount this dataset, and proceed with export-importing?
I have a checkpoint, but dunno whether the CoW mechanism can save me if i messed with this apparently system-related dataset.