Storage is at 100% out of the blue and Win11 can't access any folders

I am new to both TrueNAS as well as NAS’s in general, so please be gentle. I very recently built my first NAS and have had it up and running with TrueNAS Scale for less than a week now. Last night I heard the NAS going nuts in terms of HDD activity but didn’t think too much of it an went to sleep. As of this morning I receive an error saying that windows cannot access the NAS shared folders in file explorer. So I logged into the TrueNAS UI and it shows that my storage is not 100%, and I see a low capacity warning.

Is there any easy way to recover from this? Or do I have to delete my storage pool and create a new one. I still have the files that were on the NAS saved elsewhere so that wouldn’t be the end of the world, but I would prefer to not have to do all that work again. That and I wouldn’t feel too confident going forward in TrueNAS keeping my data safe accessible.

Thanks for any and all help.

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I’d recommend disabling any SMB services, or anything else that might access the pool in question (apps, vms, whatever) temporarily. Creating some free space by manually deleting files using CLI, and then go from there.

It is also really strange that you randomly have a pool that is 100% full - you should really investigate why that happened.

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So I went back in to disable SMB services as you advised and I found that it was already turned off, despite being set to start automatically.

When I tried to turn it back on I received the following error:

# CallError

[EFAULT] [Errno 28] No space left on device: ‘/var/db/system/samba4’

As for the storage page, when I go there I see that other than available capacity being 0 B everything seems to be happy, as far as I can tell at least. All of my drives show up in the topology box, and in the ZFS health box the Pool Status shows as Online and total ZFS error are 0.

And to you last point about investigating how this happened I really don’t know where to begin. According to the Alerts that I see at the top right of the UI the disks filled up in the middle of the night last night when everyone in my home was asleep and every computer that has access to the NAS was turned off. As far as I can tell the NAS did this to itself.

I’ll start digging into how to delete files from CLI, hopefully that’s the ticket.

SMB services won’t start of course when you’re 100% full. It requires being able to write some state to the pool. You should track down why it filled like this. If I were to hazard a guess it’s probably related to snapshots. What is the output of zfs list -o space?

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Here’s what I get when I type that in:

[truenas]> zfs list -o space
Namespace zfs not found

I don’t know if need to enter a directory before inputting that command, I really am green as a NAS user. And my Linux command line is really rusty, it’s been at least 10 years since the last time.

I just wanted to quickly add that in the Data Protection box in the Datasets section of the GUI it shows Total Snapshots: 0, so I don’t think that snapshots are the cause here.

try sudo zfs list -o space

Paste the results back here using Preformatted text </> on tool bar or Ctrl+e

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I get that “Namespace sudo not found”. I am typing this in to the root, immediately after typing in ‘cli’ at the initial prompt. Should I be in a specific directory before entering this?

Open the Linux shell, not TrueNAS CLI. I just tested in on Fangtooth 25.04.1
I didn’t need ‘sudo’ before it.

If you need to get out of TrueNAS CLI, type ‘exit’ and hit enter. Wait a bit and you should be back to the usual console screen

Are you using the console of the computer, aka keyboard, mouse and monitor or are your in the GUI and in the Shell? System menu then Shell?

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That worked! Thanks for the advice SmallBarky. Here is the result when I enter the command into the right place:

NAME                                                        AVAIL   USED  USEDSNAP  USEDDS  USEDREFRESERV  USEDCHILD
CameroNAS                                                      0B  49.3T        0B    140K             0B      49.3T
CameroNAS/.system                                              0B   133M        0B    174K             0B       133M
CameroNAS/.system/configs-ae32c386e13840b2bf9c0083275e7941     0B  1.09M        0B   1.09M             0B         0B
CameroNAS/.system/cores                                        0B   140K        0B    140K             0B         0B
CameroNAS/.system/netdata-ae32c386e13840b2bf9c0083275e7941     0B   131M        0B    131M             0B         0B
CameroNAS/.system/nfs                                          0B   163K        0B    163K             0B         0B
CameroNAS/.system/samba4                                       0B   291K        0B    291K             0B         0B
CameroNAS/NAS_Main                                             0B  49.2T        0B   49.2T             0B       169K
CameroNAS/NAS_Main/slaptop                                     0B   169K        0B    169K             0B         0B
boot-pool                                                    212G  2.84G        0B     96K             0B      2.84G
boot-pool/ROOT                                               212G  2.81G        0B     96K             0B      2.81G
boot-pool/ROOT/25.04.1                                       212G  2.81G        0B    174M             0B      2.64G
boot-pool/ROOT/25.04.1/audit                                 212G  1.40M        0B   1.40M             0B         0B
boot-pool/ROOT/25.04.1/conf                                  212G  7.05M        0B   7.05M             0B         0B
boot-pool/ROOT/25.04.1/data                                  212G   268K        0B    268K             0B         0B
boot-pool/ROOT/25.04.1/etc                                   212G  7.15M     1012K   6.16M             0B         0B
boot-pool/ROOT/25.04.1/home                                  212G   116K        0B    116K             0B         0B
boot-pool/ROOT/25.04.1/mnt                                   212G    96K        0B     96K             0B         0B
boot-pool/ROOT/25.04.1/opt                                   212G    96K        0B     96K             0B         0B
boot-pool/ROOT/25.04.1/root                                  212G   144K        0B    144K             0B         0B
boot-pool/ROOT/25.04.1/usr                                   212G  2.53G        0B   2.53G             0B         0B
boot-pool/ROOT/25.04.1/var                                   212G  95.8M      808K   5.07M             0B      89.9M
boot-pool/ROOT/25.04.1/var/ca-certificates                   212G    96K        0B     96K             0B         0B
boot-pool/ROOT/25.04.1/var/lib                               212G  27.1M      200K   26.8M             0B        96K
boot-pool/ROOT/25.04.1/var/lib/incus                         212G    96K        0B     96K             0B         0B
boot-pool/ROOT/25.04.1/var/log                               212G  62.8M        0B   12.2M             0B      50.6M
boot-pool/ROOT/25.04.1/var/log/journal                       212G  50.6M        0B   50.6M             0B         0B
boot-pool/grub                                               212G  8.42M        0B   8.42M             0B         0B

That is showing everything is in NAS_Main with 49.2TB in that pool.

You should be able to browse and check to see what is taking up the space in there.

The command ‘du’ will help you see the size of folders, subfolders, etc. Run ‘man du’ to get a description of options for using it. You may have to use ‘sudo’ before the command, depending on what console or Shell you are in.

du -h /mnt/NAS_Main should get you started. You can also look to see what files and folders are in there.

I’d suggest actually starting with du -h -d1 /mnt/NAS_Main

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So thanks to the help from everyone above and a little of my own searching I was able to delete enough files to be able to turn the SMB service back on, which allowed my to get in with windows file explorer. I have new questions now that I have though.

If I add all of the space that the various folders are reporting as taking up, it only adds up to ~26 TB of space used. Despite that, my storage on the GUI is showing as ~48 TB used and just over 1 TB available.

How can I find where/how this missing space is being taken up?

We need to know more details on your system. Is this just used for storage or do you have apps and/or VMs running on TrueNAS? If you do, what apps and/or VMs?

Browse some other threads and do the Tutorial by the Bot to get your forum trust level up so you can post images, etc.

TrueNAS-Bot
Type this in a new reply and send to bring up the tutorial, if you haven’t done it already.

@TrueNAS-Bot start tutorial

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No apps or VMs currently. I have a few that I would like to get into but so far all I’ve done is get the system set up to be a file server and nothing else. I’ll do the tutorial in the meantime.

I’ve completed the tutorial and now am able to post images. I’ve added a screenshot of what I see in the Storage page of the TrueNAS GUI, which still shows the availlable storage as being almost full. When I look at the folder in the NAS in windows file explorer their sum total comes to 14 TB.

How can I figure out where the extra space has gone?

What have you done on cleaning up files?

run sudo zfs list -o space and paste the results back using preformatted text as you did before.

You can try the following also. This should show the pool and drive info
sudo ZPOOL_SCRIPTS_AS_ROOT=1 zpool status -vLtsc lsblk,serial,smartx,smart

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The Windows data is a share, which shows you using almost all 14 TB of the share. If it’s really the whole pool as the zfs list shows, then, the Windows numbers are for sure wrong as you don’t have 14TB storage. Maybe you set a quota? Not sure how Windows would show that. I don’t use quotas so maybe one is set?

How big are the drives in the Raidz1?

Well, curious for me is the topology section shows 10.91TiB. Mine shows the same in topology and usage as far as total capacity.

Still want to see the results of:

du -h -d1 /mnt/NAS_Main

And did you ever add another drive to your existing raidz1 pool?

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I use command line in the console of the computer to delete a few files in the Movies folder, enough to re-enable the SMB service, which let me use File Explorer to access the remaining files from my Windows PC again.

Here is the result from the first command you requested:

NAME                                                        AVAIL   USED  USEDSNAP  USEDDS  USEDREFRESERV  USEDCHILD
CameroNAS                                                   1.07T  48.1T        0B    140K             0B      48.1T
CameroNAS/.system                                           1.07T   133M        0B    465K             0B       133M
CameroNAS/.system/configs-ae32c386e13840b2bf9c0083275e7941  1.07T  1.09M        0B   1.09M             0B         0B
CameroNAS/.system/cores                                     1024M   140K        0B    140K             0B         0B
CameroNAS/.system/netdata-ae32c386e13840b2bf9c0083275e7941  1.07T   131M        0B    131M             0B         0B
CameroNAS/.system/nfs                                       1.07T   163K        0B    163K             0B         0B
CameroNAS/.system/samba4                                    1.07T   291K        0B    291K             0B         0B
CameroNAS/NAS_Main                                          1.07T  48.0T        0B   48.0T             0B       169K
CameroNAS/NAS_Main/slaptop                                  1.07T   169K        0B    169K             0B         0B
boot-pool                                                    212G  2.90G        0B     96K             0B      2.90G
boot-pool/ROOT                                               212G  2.86G        0B     96K             0B      2.86G
boot-pool/ROOT/25.04.1                                       212G  2.86G        0B    174M             0B      2.69G
boot-pool/ROOT/25.04.1/audit                                 212G  2.01M        0B   2.01M             0B         0B
boot-pool/ROOT/25.04.1/conf                                  212G  7.05M        0B   7.05M             0B         0B
boot-pool/ROOT/25.04.1/data                                  212G   268K        0B    268K             0B         0B
boot-pool/ROOT/25.04.1/etc                                   212G  7.15M     1012K   6.16M             0B         0B
boot-pool/ROOT/25.04.1/home                                  212G   120K        0B    120K             0B         0B
boot-pool/ROOT/25.04.1/mnt                                   212G    96K        0B     96K             0B         0B
boot-pool/ROOT/25.04.1/opt                                   212G    96K        0B     96K             0B         0B
boot-pool/ROOT/25.04.1/root                                  212G   144K        0B    144K             0B         0B
boot-pool/ROOT/25.04.1/usr                                   212G  2.53G        0B   2.53G             0B         0B
boot-pool/ROOT/25.04.1/var                                   212G   148M      808K   5.07M             0B       142M
boot-pool/ROOT/25.04.1/var/ca-certificates                   212G    96K        0B     96K             0B         0B
boot-pool/ROOT/25.04.1/var/lib                               212G  27.1M      200K   26.8M             0B        96K
boot-pool/ROOT/25.04.1/var/lib/incus                         212G    96K        0B     96K             0B         0B
boot-pool/ROOT/25.04.1/var/log                               212G   115M        0B   65.2M             0B      49.7M
boot-pool/ROOT/25.04.1/var/log/journal                       212G  49.7M        0B   49.7M             0B         0B
boot-pool/grub                                               212G  8.42M        0B   8.42M             0B         0B
truenas_admin@truenas[~]$ 

And here is the result from the second command:

  pool: CameroNAS
 state: ONLINE
config:

        NAME         STATE     READ WRITE CKSUM  SLOW    size  vendor                  model            serial  pwr_cyc  hours_on  health  temp  nvme_err  realloc  pend_sec  off_ucor  ata_err  rep_ucor  cmd_to
        CameroNAS    ONLINE       0     0     0     -
          raidz1-0   ONLINE       0     0     0     -
            sda1     ONLINE       0     0     0     0   10.9T     ATA  WDC WD120EFBX-68B0EN0          D7JUBUPN        3       317  PASSED    36         -        0         0         0        -         -       -  (trim unsupported)
            sde1     ONLINE       0     0     0     0   10.9T     ATA  WDC WD120EFBX-68B0EN0          5QKBHN3B     2274     19754  PASSED    39         -        0         0         0        -         -       -  (trim unsupported)
            sdd1     ONLINE       0     0     0     0   10.9T     ATA  WDC WD120EFBX-68B0EN0          5QJ6K16B     2303     21499  PASSED    37         -        0         0         0        -         -       -  (trim unsupported)
            sdb1     ONLINE       0     0     0     0   10.9T     ATA  WDC WD120EFBX-68B0EN0          D7JVW4HN        3       317  PASSED    32         -        0         0         0        -         -       -  (trim unsupported)
        cache
          nvme0n1p1  ONLINE       0     0     0     0  931.5G       -     WD Blue SN5000 1TB      252114804244        6       317  PASSED    35         0        -         -         -        -         -       -  (untrimmed)

errors: No known data errors

  pool: boot-pool
 state: ONLINE
  scan: scrub repaired 0B in 00:00:06 with 0 errors on Sat Jul 19 03:45:08 2025
config:

        NAME        STATE     READ WRITE CKSUM  SLOW    size  vendor                  model            serial  pwr_cyc  hours_on  health  temp  nvme_err  realloc  pend_sec  off_ucor  ata_err  rep_ucor  cmd_to
        boot-pool   ONLINE       0     0     0     -
          sdc3      ONLINE       0     0     0     0  223.6G     ATA  KINGSTON SA400S37240G  50026B72830CF619        6       317  PASSED    26         -        -         -         -        -         0       -  (untrimmed)

errors: No known data errors

@sfatula I haven’t set any quotas, so as far as I am aware Windows should see the whole pool. It did initally at least, I was able to see the correct amount of available space when I first set everything up.

The drives in the Raidz1 are 4 x 12 TB.

And here are the results of the command you requested:

du: cannot read directory '/mnt/CameroNAS/NAS_Main/basement': Permission denied
512     /mnt/CameroNAS/NAS_Main/basement
du: cannot read directory '/mnt/CameroNAS/NAS_Main/slaptop': Permission denied
512     /mnt/CameroNAS/NAS_Main/slaptop
2.5T    /mnt/CameroNAS/NAS_Main/Movies
4.5T    /mnt/CameroNAS/NAS_Main/TV
4.5T    /mnt/CameroNAS/NAS_Main/Incognito
du: cannot read directory '/mnt/CameroNAS/NAS_Main/playroom': Permission denied
12K     /mnt/CameroNAS/NAS_Main/playroom
1.9T    /mnt/CameroNAS/NAS_Main/Kids Stuff
217G    /mnt/CameroNAS/NAS_Main/Documentaries
802G    /mnt/CameroNAS/NAS_Main/Pictures
du: cannot read directory '/mnt/CameroNAS/NAS_Main/mainuser': Permission denied
12K     /mnt/CameroNAS/NAS_Main/mainuser
15T     /mnt/CameroNAS/NAS_Main