Disk space reported incorrectly

TrueNas scale ElectricEel-24.10.2
1 Pool with 5x 4 TB disk using Raidz1 + 1 300 Gb disk for Dedup
2 Dataset inside the pool

Disk usage it show used a bit over 11TiB while i expect the real used space to be in between 5 and 6
zfs listoutput for the pool below

--------------------------------------------------
admin@plex-truenas[~]$ sudo zfs list|grep NAS
NAS                                                                 11.1T  3.27T   179K  /mnt/NAS
NAS/.system                                                         2.12G  3.27T  1.47G  legacy
NAS/.system/configs-ae32c386e13840b2bf9c0083275e7941                27.0M  3.27T  27.0M  legacy
NAS/.system/cores                                                    153K  1024M   153K  legacy
NAS/.system/netdata-ae32c386e13840b2bf9c0083275e7941                 642M  3.27T   642M  legacy
NAS/.system/nfs                                                      236K  3.27T   236K  legacy
NAS/.system/samba4                                                  1.17M  3.27T   543K  legacy
NAS/PLEX                                                            5.52T  3.27T  5.52T  /mnt/NAS/PLEX
NAS/ix-applications                                                 9.16G  3.27T   850K  /mnt/NAS/ix-applications
NAS/ix-applications/catalogs                                        62.7M  3.27T  62.7M  /mnt/NAS/ix-applications/catalogs
NAS/ix-applications/default_volumes                                  153K  3.27T   153K  /mnt/NAS/ix-applications/default_volumes
NAS/ix-applications/k3s                                             7.20G  3.27T  7.20G  /mnt/NAS/ix-applications/k3s
NAS/ix-applications/k3s/kubelet                                      939K  3.27T   939K  legacy
NAS/ix-applications/releases                                        1.89G  3.27T   932M  /mnt/NAS/ix-applications/releases
NAS/ix-applications/releases/filebrowser                            1.37M  3.27T   166K  /mnt/NAS/ix-applications/releases/filebrowser
NAS/ix-applications/releases/filebrowser/charts                      754K  3.27T   754K  /mnt/NAS/ix-applications/releases/filebrowser/charts
NAS/ix-applications/releases/filebrowser/volumes                     479K  3.27T   153K  /mnt/NAS/ix-applications/releases/filebrowser/volumes
NAS/ix-applications/releases/filebrowser/volumes/ix_volumes          326K  3.27T   153K  /mnt/NAS/ix-applications/releases/filebrowser/volumes/ix_volumes
NAS/ix-applications/releases/filebrowser/volumes/ix_volumes/config   173K  3.27T   173K  /mnt/NAS/ix-applications/releases/filebrowser/volumes/ix_volumes/config
NAS/ix-applications/releases/netdata                                3.03M  3.27T   166K  /mnt/NAS/ix-applications/releases/netdata
NAS/ix-applications/releases/netdata/charts                         1.78M  3.27T  1.78M  /mnt/NAS/ix-applications/releases/netdata/charts
NAS/ix-applications/releases/netdata/volumes                        1.09M  3.27T   153K  /mnt/NAS/ix-applications/releases/netdata/volumes
NAS/ix-applications/releases/netdata/volumes/ix_volumes              959K  3.27T   166K  /mnt/NAS/ix-applications/releases/netdata/volumes/ix_volumes
NAS/ix-applications/releases/netdata/volumes/ix_volumes/cache        524K  3.27T  1.64G  /mnt/NAS/ix-applications/releases/netdata/volumes/ix_volumes/cache
NAS/ix-applications/releases/netdata/volumes/ix_volumes/config       115K  3.27T   198K  /mnt/NAS/ix-applications/releases/netdata/volumes/ix_volumes/config
NAS/ix-applications/releases/netdata/volumes/ix_volumes/lib          153K  3.27T   217K  /mnt/NAS/ix-applications/releases/netdata/volumes/ix_volumes/lib
NAS/ix-applications/releases/plex                                   34.5M  3.27T   166K  /mnt/NAS/ix-applications/releases/plex
NAS/ix-applications/releases/plex/charts                            1.27M  3.27T  1.27M  /mnt/NAS/ix-applications/releases/plex/charts
NAS/ix-applications/releases/plex/volumes                           33.0M  3.27T   153K  /mnt/NAS/ix-applications/releases/plex/volumes
NAS/ix-applications/releases/plex/volumes/ix_volumes                32.9M  3.27T   166K  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes
NAS/ix-applications/releases/plex/volumes/ix_volumes/config         32.4M  3.27T  4.95G  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes/config
NAS/ix-applications/releases/plex/volumes/ix_volumes/data            102K  3.27T   153K  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes/data
NAS/ix-applications/releases/plex/volumes/ix_volumes/logs           89.5K  3.27T   153K  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes/logs
NAS/ix-applications/releases/plex/volumes/ix_volumes/transcode       141K  3.27T   555M  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes/transcode
NAS/ix-applications/releases/syncthing                               969M  3.27T   166K  /mnt/NAS/ix-applications/releases/syncthing
NAS/ix-applications/releases/syncthing/charts                        959K  3.27T   959K  /mnt/NAS/ix-applications/releases/syncthing/charts
NAS/ix-applications/releases/syncthing/volumes                       968M  3.27T   153K  /mnt/NAS/ix-applications/releases/syncthing/volumes
NAS/ix-applications/releases/syncthing/volumes/ix_volumes            967M  3.27T   153K  /mnt/NAS/ix-applications/releases/syncthing/volumes/ix_volumes
NAS/ix-applications/releases/syncthing/volumes/ix_volumes/config     967M  3.27T   967M  /mnt/NAS/ix-applications/releases/syncthing/volumes/ix_volumes/config
NAS/ix-apps                                                         5.60T  3.27T   185K  /mnt/.ix-apps
NAS/ix-apps/app_configs                                             6.78M  3.27T  6.78M  /mnt/.ix-apps/app_configs
NAS/ix-apps/app_mounts                                              5.60T  3.27T   192K  /mnt/.ix-apps/app_mounts
NAS/ix-apps/app_mounts/filebrowser                                   422K  3.27T   153K  /mnt/.ix-apps/app_mounts/filebrowser
NAS/ix-apps/app_mounts/filebrowser/config                            268K  3.27T   173K  /mnt/.ix-apps/app_mounts/filebrowser/config
NAS/ix-apps/app_mounts/netdata                                      7.95G  3.27T   179K  /mnt/.ix-apps/app_mounts/netdata
NAS/ix-apps/app_mounts/netdata/cache                                7.95G  3.27T  1.73G  /mnt/.ix-apps/app_mounts/netdata/cache
NAS/ix-apps/app_mounts/netdata/config                               1.09M  3.27T   198K  /mnt/.ix-apps/app_mounts/netdata/config
NAS/ix-apps/app_mounts/netdata/lib                                  1.66M  3.27T   281K  /mnt/.ix-apps/app_mounts/netdata/lib
NAS/ix-apps/app_mounts/plex                                         5.59T  3.27T   179K  /mnt/.ix-apps/app_mounts/plex
NAS/ix-apps/app_mounts/plex/config                                  15.3G  3.27T  5.69G  /mnt/.ix-apps/app_mounts/plex/config
NAS/ix-apps/app_mounts/plex/data                                    5.57T  3.27T   153K  /mnt/.ix-apps/app_mounts/plex/data
NAS/ix-apps/app_mounts/plex/logs                                    20.0M  3.27T  8.34M  /mnt/.ix-apps/app_mounts/plex/logs
NAS/ix-apps/app_mounts/plex/transcode                                649M  3.27T   555M  /mnt/.ix-apps/app_mounts/plex/transcode
NAS/ix-apps/app_mounts/syncthing                                    1.92G  3.27T   153K  /mnt/.ix-apps/app_mounts/syncthing
NAS/ix-apps/app_mounts/syncthing/config                             1.92G  3.27T   973M  /mnt/.ix-apps/app_mounts/syncthing/config
NAS/ix-apps/docker                                                  1.98G  3.27T  1.98G  /mnt/.ix-apps/docker
NAS/ix-apps/truenas_catalog                                          260M  3.27T   260M  /mnt/.ix-apps/truenas_catalog
------------------------------------------------------------------------------

For some reason this appear to show 5.57 TB usage
/mnt/.ix-apps/app_mounts/plex/data

but then if i look inside is empty

----------------------------------------------------------
admin@plex-truenas[~]$ ls -la /mnt/.ix-apps/app_mounts/plex/data
total 1
drwxr-xr-x 2 apps apps 2 Mar 22 19:14 .
drwxr-xr-x 6 root root 6 Feb  4 11:43 ..

admin@plex-truenas[~]$ du /mnt/.ix-apps/app_mounts/plex/data
1       /mnt/.ix-apps/app_mounts/plex/data

why is that? What am I missing?

Please post your data using Preformatted Text (</>) or Ctrl+e going forward. It just makes it easier to read.

Do you have snapshots? Snapshots can be keeping the space used for filesystem changes. You also mention Dedup?

For DeDup information, please supply the output of this command in CODE tags, (aka Preformatted Text):
zpool list -v NAS

admin@plex-truenas[~]$ sudo zpool list -v NAS
NAME                                       SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
NAS                                       18.5T  13.9T  4.54T        -         -     1%    75%  1.00x    ONLINE  /mnt
  raidz1-0                                18.2T  13.9T  4.25T        -         -     1%  76.6%      -    ONLINE
    a240e7fb-47fd-4f03-8714-4117c19b45a9  3.64T      -      -        -         -      -      -      -    ONLINE
    c51022cb-c068-415f-9336-5756271ce8a5  3.64T      -      -        -         -      -      -      -    ONLINE
    6e7ef721-1d20-4778-97f3-dcc1da884030  3.64T      -      -        -         -      -      -      -    ONLINE
    dd44c3f3-fa2a-4be3-8d88-6ba1eb2cd7f4  3.64T      -      -        -         -      -      -      -    ONLINE
    77a1e80d-eec3-48c1-a66a-956cf83effef  3.64T      -      -        -         -      -      -      -    ONLINE
dedup                                         -      -      -        -         -      -      -      -         -
  643ad991-1a5c-496a-bed4-13fd35c0f2d6     298G      0   298G        -         -     0%  0.00%      -    ONLINE

``

no snapshot

:scream:
If anything happens to the single dedup vdev, you lose the whole pool.

I’m aware. But that was not the question in this post

Looks like you don’t even use DeDup. It has to be enabled, preferably with a higher level checksum than the default.

Snapshots are generally the cause of higher than expected space usage. Please supply the output of the following command in CODE tags;
sudo zfs list -t all -r NAS

I’m relatively new to TrueNAs and still experimenting on the dedup part I still understanding how it works, so if you can point me to some article explaining how to actually enable it i’ll appreciate it
As far as I can see there are no snapshot (I had but I removed)
for some context the folder data that is reporting the 5,5 TB had data in it and I deleted manually from CLI but the space usage did not change

here is the output requested

admin@plex-truenas[~]$ sudo zfs list -t all -r NAS
NAME                                                                                              USED  AVAIL  REFER  MOUNTPOINT
NAS                                                                                              11.1T  3.27T   179K  /mnt/NAS
NAS/.system                                                                                      2.09G  3.27T  1.47G  legacy
NAS/.system/configs-ae32c386e13840b2bf9c0083275e7941                                             27.1M  3.27T  27.1M  legacy
NAS/.system/cores                                                                                 153K  1024M   153K  legacy
NAS/.system/netdata-ae32c386e13840b2bf9c0083275e7941                                              615M  3.27T   615M  legacy
NAS/.system/nfs                                                                                   236K  3.27T   236K  legacy
NAS/.system/samba4                                                                               1.17M  3.27T   543K  legacy
NAS/.system/samba4@update--2025-02-03-10-11--SCALE-24.04.2                                        262K      -   435K  -
NAS/.system/samba4@update--2025-02-04-08-40--SCALE-24.04.2.5                                      364K      -   537K  -
NAS/PLEX                                                                                         5.52T  3.27T  5.52T  /mnt/NAS/PLEX
NAS/ix-applications                                                                              9.16G  3.27T   850K  /mnt/NAS/ix-applications
NAS/ix-applications/catalogs                                                                     62.7M  3.27T  62.7M  /mnt/NAS/ix-applications/catalogs
NAS/ix-applications/default_volumes                                                               153K  3.27T   153K  /mnt/NAS/ix-applications/default_volumes
NAS/ix-applications/k3s                                                                          7.20G  3.27T  7.20G  /mnt/NAS/ix-applications/k3s
NAS/ix-applications/k3s/kubelet                                                                   939K  3.27T   939K  legacy
NAS/ix-applications/releases                                                                     1.89G  3.27T   932M  /mnt/NAS/ix-applications/releases
NAS/ix-applications/releases/filebrowser                                                         1.37M  3.27T   166K  /mnt/NAS/ix-applications/releases/filebrowser
NAS/ix-applications/releases/filebrowser/charts                                                   754K  3.27T   754K  /mnt/NAS/ix-applications/releases/filebrowser/charts
NAS/ix-applications/releases/filebrowser/volumes                                                  479K  3.27T   153K  /mnt/NAS/ix-applications/releases/filebrowser/volumes
NAS/ix-applications/releases/filebrowser/volumes/ix_volumes                                       326K  3.27T   153K  /mnt/NAS/ix-applications/releases/filebrowser/volumes/ix_volumes
NAS/ix-applications/releases/filebrowser/volumes/ix_volumes/config                                173K  3.27T   173K  /mnt/NAS/ix-applications/releases/filebrowser/volumes/ix_volumes/config
NAS/ix-applications/releases/netdata                                                             3.03M  3.27T   166K  /mnt/NAS/ix-applications/releases/netdata
NAS/ix-applications/releases/netdata/charts                                                      1.78M  3.27T  1.78M  /mnt/NAS/ix-applications/releases/netdata/charts
NAS/ix-applications/releases/netdata/volumes                                                     1.09M  3.27T   153K  /mnt/NAS/ix-applications/releases/netdata/volumes
NAS/ix-applications/releases/netdata/volumes/ix_volumes                                           959K  3.27T   166K  /mnt/NAS/ix-applications/releases/netdata/volumes/ix_volumes
NAS/ix-applications/releases/netdata/volumes/ix_volumes/cache                                     524K  3.27T  1.64G  /mnt/NAS/ix-applications/releases/netdata/volumes/ix_volumes/cache
NAS/ix-applications/releases/netdata/volumes/ix_volumes/config                                    115K  3.27T   198K  /mnt/NAS/ix-applications/releases/netdata/volumes/ix_volumes/config
NAS/ix-applications/releases/netdata/volumes/ix_volumes/lib                                       153K  3.27T   217K  /mnt/NAS/ix-applications/releases/netdata/volumes/ix_volumes/lib
NAS/ix-applications/releases/plex                                                                34.5M  3.27T   166K  /mnt/NAS/ix-applications/releases/plex
NAS/ix-applications/releases/plex/charts                                                         1.27M  3.27T  1.27M  /mnt/NAS/ix-applications/releases/plex/charts
NAS/ix-applications/releases/plex/volumes                                                        33.0M  3.27T   153K  /mnt/NAS/ix-applications/releases/plex/volumes
NAS/ix-applications/releases/plex/volumes/ix_volumes                                             32.9M  3.27T   166K  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes
NAS/ix-applications/releases/plex/volumes/ix_volumes/config                                      32.4M  3.27T  4.95G  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes/config
NAS/ix-applications/releases/plex/volumes/ix_volumes/data                                         102K  3.27T   153K  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes/data
NAS/ix-applications/releases/plex/volumes/ix_volumes/logs                                        89.5K  3.27T   153K  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes/logs
NAS/ix-applications/releases/plex/volumes/ix_volumes/transcode                                    141K  3.27T   555M  /mnt/NAS/ix-applications/releases/plex/volumes/ix_volumes/transcode
NAS/ix-applications/releases/syncthing                                                            969M  3.27T   166K  /mnt/NAS/ix-applications/releases/syncthing
NAS/ix-applications/releases/syncthing/charts                                                     959K  3.27T   959K  /mnt/NAS/ix-applications/releases/syncthing/charts
NAS/ix-applications/releases/syncthing/volumes                                                    968M  3.27T   153K  /mnt/NAS/ix-applications/releases/syncthing/volumes
NAS/ix-applications/releases/syncthing/volumes/ix_volumes                                         967M  3.27T   153K  /mnt/NAS/ix-applications/releases/syncthing/volumes/ix_volumes
NAS/ix-applications/releases/syncthing/volumes/ix_volumes/config                                  967M  3.27T   967M  /mnt/NAS/ix-applications/releases/syncthing/volumes/ix_volumes/config
NAS/ix-apps                                                                                      5.60T  3.27T   185K  /mnt/.ix-apps
NAS/ix-apps/app_configs                                                                          6.78M  3.27T  6.78M  /mnt/.ix-apps/app_configs
NAS/ix-apps/app_mounts                                                                           5.60T  3.27T   192K  /mnt/.ix-apps/app_mounts
NAS/ix-apps/app_mounts/filebrowser                                                                422K  3.27T   153K  /mnt/.ix-apps/app_mounts/filebrowser
NAS/ix-apps/app_mounts/filebrowser@1.2.8                                                            0B      -   153K  -
NAS/ix-apps/app_mounts/filebrowser/config                                                         268K  3.27T   173K  /mnt/.ix-apps/app_mounts/filebrowser/config
NAS/ix-apps/app_mounts/filebrowser/config@1.2.8                                                  95.9K      -   173K  -
NAS/ix-apps/app_mounts/netdata                                                                   8.08G  3.27T   179K  /mnt/.ix-apps/app_mounts/netdata
NAS/ix-apps/app_mounts/netdata@1.2.13                                                               0B      -   179K  -
NAS/ix-apps/app_mounts/netdata@1.2.14                                                               0B      -   179K  -
NAS/ix-apps/app_mounts/netdata@1.2.18                                                               0B      -   179K  -
NAS/ix-apps/app_mounts/netdata/cache                                                             8.08G  3.27T  1.73G  /mnt/.ix-apps/app_mounts/netdata/cache
NAS/ix-apps/app_mounts/netdata/cache@5                                                           1.33G      -  1.41G  -
NAS/ix-apps/app_mounts/netdata/cache@6                                                            852M      -  1.42G  -
NAS/ix-apps/app_mounts/netdata/cache@7                                                            968M      -  1.50G  -
NAS/ix-apps/app_mounts/netdata/cache@ix-applications-backup-system-update--2025-02-03_10:11:11    131M      -  1.63G  -
NAS/ix-apps/app_mounts/netdata/cache@9                                                           17.9M      -  1.62G  -
NAS/ix-apps/app_mounts/netdata/cache@ix-applications-backup-system-update--2025-02-04_08:40:52   14.2M      -  1.64G  -
NAS/ix-apps/app_mounts/netdata/cache@1.2.13                                                      15.4M      -  1.64G  -
NAS/ix-apps/app_mounts/netdata/cache@1.2.14                                                       830M      -  1.72G  -
NAS/ix-apps/app_mounts/netdata/cache@1.2.18                                                       158M      -  1.73G  -
NAS/ix-apps/app_mounts/netdata/config                                                            1.09M  3.27T   198K  /mnt/.ix-apps/app_mounts/netdata/config
NAS/ix-apps/app_mounts/netdata/config@5                                                           102K      -   198K  -
NAS/ix-apps/app_mounts/netdata/config@6                                                           102K      -   198K  -
NAS/ix-apps/app_mounts/netdata/config@7                                                           102K      -   198K  -
NAS/ix-apps/app_mounts/netdata/config@ix-applications-backup-system-update--2025-02-03_10:11:11   102K      -   198K  -
NAS/ix-apps/app_mounts/netdata/config@9                                                           102K      -   198K  -
NAS/ix-apps/app_mounts/netdata/config@ix-applications-backup-system-update--2025-02-04_08:40:52   102K      -   198K  -
NAS/ix-apps/app_mounts/netdata/config@1.2.13                                                      102K      -   198K  -
NAS/ix-apps/app_mounts/netdata/config@1.2.14                                                      102K      -   198K  -
NAS/ix-apps/app_mounts/netdata/config@1.2.18                                                      102K      -   198K  -
NAS/ix-apps/app_mounts/netdata/lib                                                               1.66M  3.27T   281K  /mnt/.ix-apps/app_mounts/netdata/lib
NAS/ix-apps/app_mounts/netdata/lib@5                                                              141K      -   192K  -
NAS/ix-apps/app_mounts/netdata/lib@6                                                              141K      -   192K  -
NAS/ix-apps/app_mounts/netdata/lib@7                                                              141K      -   192K  -
NAS/ix-apps/app_mounts/netdata/lib@ix-applications-backup-system-update--2025-02-03_10:11:11      141K      -   192K  -
NAS/ix-apps/app_mounts/netdata/lib@9                                                              153K      -   204K  -
NAS/ix-apps/app_mounts/netdata/lib@ix-applications-backup-system-update--2025-02-04_08:40:52      166K      -   217K  -
NAS/ix-apps/app_mounts/netdata/lib@1.2.13                                                         166K      -   217K  -
NAS/ix-apps/app_mounts/netdata/lib@1.2.14                                                         192K      -   275K  -
NAS/ix-apps/app_mounts/netdata/lib@1.2.18                                                         179K      -   262K  -
NAS/ix-apps/app_mounts/plex                                                                      5.59T  3.27T   179K  /mnt/.ix-apps/app_mounts/plex
NAS/ix-apps/app_mounts/plex@1.1.14                                                                  0B      -   179K  -
NAS/ix-apps/app_mounts/plex/config                                                               15.6G  3.27T  5.69G  /mnt/.ix-apps/app_mounts/plex/config
NAS/ix-apps/app_mounts/plex/config@11                                                            2.23G      -  4.18G  -
NAS/ix-apps/app_mounts/plex/config@17                                                            1.95G      -  4.11G  -
NAS/ix-apps/app_mounts/plex/config@20                                                            1.79G      -  4.93G  -
NAS/ix-apps/app_mounts/plex/config@ix-applications-backup-system-update--2025-02-03_10:11:11      288M      -  5.20G  -
NAS/ix-apps/app_mounts/plex/config@ix-applications-backup-system-update--2025-02-04_08:40:52     22.2M      -  4.95G  -
NAS/ix-apps/app_mounts/plex/config@1.1.14                                                        1.22G      -  5.36G  -
NAS/ix-apps/app_mounts/plex/data                                                                 5.57T  3.27T   153K  /mnt/.ix-apps/app_mounts/plex/data
NAS/ix-apps/app_mounts/plex/data@11                                                               729K      -  5.07T  -
NAS/ix-apps/app_mounts/plex/data@17                                                               614K      -  5.14T  -
NAS/ix-apps/app_mounts/plex/data@20                                                              1.07M      -  5.25T  -
NAS/ix-apps/app_mounts/plex/data@ix-applications-backup-system-update--2025-02-03_10:11:11        307K      -  5.57T  -
NAS/ix-apps/app_mounts/plex/data@ix-applications-backup-system-update--2025-02-04_08:40:52       12.8K      -  5.57T  -
NAS/ix-apps/app_mounts/plex/data@1.1.14                                                          12.8K      -  5.57T  -
NAS/ix-apps/app_mounts/plex/logs                                                                 26.6M  3.27T  14.9M  /mnt/.ix-apps/app_mounts/plex/logs
NAS/ix-apps/app_mounts/plex/logs@11                                                                 0B      -   153K  -
NAS/ix-apps/app_mounts/plex/logs@17                                                                 0B      -   153K  -
NAS/ix-apps/app_mounts/plex/logs@20                                                                 0B      -   153K  -
NAS/ix-apps/app_mounts/plex/logs@ix-applications-backup-system-update--2025-02-03_10:11:11          0B      -   153K  -
NAS/ix-apps/app_mounts/plex/logs@ix-applications-backup-system-update--2025-02-04_08:40:52          0B      -   153K  -
NAS/ix-apps/app_mounts/plex/logs@1.1.14                                                          11.6M      -  12.6M  -
NAS/ix-apps/app_mounts/plex/transcode                                                             649M  3.27T   555M  /mnt/.ix-apps/app_mounts/plex/transcode
NAS/ix-apps/app_mounts/plex/transcode@11                                                          166K      -   555M  -
NAS/ix-apps/app_mounts/plex/transcode@17                                                         92.4M      -   648M  -
NAS/ix-apps/app_mounts/plex/transcode@20                                                          179K      -   555M  -
NAS/ix-apps/app_mounts/plex/transcode@ix-applications-backup-system-update--2025-02-03_10:11:11   179K      -   555M  -
NAS/ix-apps/app_mounts/plex/transcode@ix-applications-backup-system-update--2025-02-04_08:40:52   179K      -   555M  -
NAS/ix-apps/app_mounts/plex/transcode@1.1.14                                                      192K      -   555M  -
NAS/ix-apps/app_mounts/syncthing                                                                 1.92G  3.27T   153K  /mnt/.ix-apps/app_mounts/syncthing
NAS/ix-apps/app_mounts/syncthing@1.1.11                                                             0B      -   153K  -
NAS/ix-apps/app_mounts/syncthing/config                                                          1.92G  3.27T   973M  /mnt/.ix-apps/app_mounts/syncthing/config
NAS/ix-apps/app_mounts/syncthing/config@1.1.11                                                    995M      -   995M  -
NAS/ix-apps/docker                                                                               1.98G  3.27T  1.98G  /mnt/.ix-apps/docker
NAS/ix-apps/truenas_catalog                                                                       262M  3.27T   262M  /mnt/.ix-apps/truenas_catalog

In general, if you have to ask about ZFS DeDup, you should not be using it. Their is an improved version coming out soon, Fast DeDup. But I won’t use it for at least a year after release. Let all the others be guinea pigs.

ZFS DeDup can lead to data loss if used improperly. We had had occasional people get their DeDupped Datasets so large they can’t import them after crash, reboot or update. That is because other services may take up memory that is eventually needed for the DeDup table on pool import.

However, the user can’t import the pool to fix the problem until the have more memory. Catch 22.

The Special Allocation Device you have allocated for DeDup does not over-come the need for memory. Just improves access to the DeDup table during import and during writes that are DeDupped. I vaguely recall the ability to use an L2ARC device as a spill location for DeDup memory. But, don’t ask me the details because that is all I have.

Here is what I wrote some years ago about De-Dup:

As for your space usage, seems like Plex doubled up your media. You have to be very careful fixing this, because I am assuming you don’t want to loose any of your media. Here is what I mean:

NAS/PLEX                                                            5.52T  3.27T  5.52T  /mnt/NAS/PLEX
...
NAS/ix-apps/app_mounts/plex/data                                    5.57T  3.27T   153K  /mnt/.ix-apps/app_mounts/plex/data

I do love the title of the article :grin: so I’ll leave disable for now, and one day I’ll rebuild the pool I’ll reassigned the disk differently because from some research I did there is no way to unassign the dedup disk. As for space usage yes I reached the same conclusion but data inside the ix pool is empty I can’t understand what is taking space.
I might end un rebuilt the pool ( have some issue with the disks for the backup, once fixed and ensured backup is done I’ll probably rebuild. Any advice what would be best usage of that 300 gb disk? ( As you probably understood the pool is entirely dedicated for Plex)