Root filesystem (local) filling up on Proxmox host without visible files

jgabrielpb · 2025-10-25T01:08:50+0200

One of my proxmox nodes, the root filesystem (/) suddenly reports 170 GB used, even though no large files are present.

The problem persists through reboots and normal cleanup routines (apt autoclean, logrotate, etc.), but the reported disk usage does not match the actual file content.

Code:

# df -h /
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/pve-root  226G  168G   48G  78% /

# ncdu /
Total disk usage: 6.4 GiB

The discrepancy suggests the kernel is counting something as “used space” that’s not visible to user tools.

Code:

root@proxmox1:~# cat /etc/pve/storage.cfg
dir: local
        path /var/lib/vz
        content images,rootdir,vztmpl
        shared 0

nfs: data-vm
        export /data-vm
        path /mnt/pve/data-vm
        server 192.168.100.115
        content rootdir,images
        prune-backups keep-all=1

nfs: backup-cloud
        export /backup-cloud
        path /mnt/pve/backup-cloud
        server 192.168.100.115
        content backup
        prune-backups keep-all=1

nfs: backup-local
        export /backup-local
        path /mnt/pve/backup-local
        server 192.168.100.115
        content backup
        prune-backups keep-all=1

nfs: backup-ha
        export /backup-ha
        path /mnt/pve/backup-ha
        server 192.168.100.115
        content images,rootdir
        prune-backups keep-all=1

nfs: images-vm
        export /images-vm
        path /mnt/pve/images-vm
        server 192.168.100.115
        content iso,images,vztmpl
        prune-backups keep-all=1

nfs: media-downloads
        export /media-downloads
        path /mnt/pve/media-downloads
        server 192.168.100.115
        content rootdir
        prune-backups keep-all=1

nfs: media-movies
        export /media-movies
        path /mnt/pve/media-movies
        server 192.168.100.115
        content rootdir
        prune-backups keep-all=1

nfs: media-shows
        export /media-shows
        path /mnt/pve/media-shows
        server 192.168.100.115
        content rootdir
        prune-backups keep-all=1

nfs: media-frigate
        export /media-frigate
        path /mnt/pve/media-frigate
        server 192.168.100.115
        content images,rootdir
        prune-backups keep-all=1

zfspool: fast-vmdata
        pool fast-vmdata
        content images,rootdir
        mountpoint /fast-vmdata
        sparse 0

dir: backup-vmdata
        path /fast-vmdata/backup
        content backup
        prune-backups keep-all=1
        shared 0

Code:

root@proxmox1:~# df -h
Filesystem                        Size  Used Avail Use% Mounted on
udev                               32G     0   32G   0% /dev
tmpfs                             6.3G  3.2M  6.3G   1% /run
/dev/mapper/pve-root              226G  168G   48G  78% /
tmpfs                              32G   72M   32G   1% /dev/shm
tmpfs                             5.0M     0  5.0M   0% /run/lock
efivarfs                          128K   55K   69K  45% /sys/firmware/efi/efivars
/dev/nvme0n1p2                   1022M   12M 1011M   2% /boot/efi
fast-vmdata                       807G   34G  774G   5% /fast-vmdata
fast-vmdata/subvol-103-disk-0     2.0G  775M  1.3G  38% /fast-vmdata/subvol-103-disk-0
fast-vmdata/subvol-105-disk-0     4.0G  1.1G  3.0G  26% /fast-vmdata/subvol-105-disk-0
/dev/fuse                         128M   44K  128M   1% /etc/pve
192.168.100.115:/backup-cloud      15T  1.6T   13T  11% /mnt/pve/backup-cloud
192.168.100.115:/backup-local      15T  1.6T   13T  11% /mnt/pve/backup-local
192.168.100.115:/media-movies      15T  1.6T   13T  11% /mnt/pve/media-movies
192.168.100.115:/data-vm           15T  1.6T   13T  11% /mnt/pve/data-vm
192.168.100.115:/media-frigate     15T  1.6T   13T  11% /mnt/pve/media-frigate
192.168.100.115:/images-vm         15T  1.6T   13T  11% /mnt/pve/images-vm
192.168.100.115:/media-downloads   15T  1.6T   13T  11% /mnt/pve/media-downloads
192.168.100.115:/backup-ha         15T  1.6T   13T  11% /mnt/pve/backup-ha
192.168.100.115:/media-shows       15T  1.6T   13T  11% /mnt/pve/media-shows
tmpfs                             6.3G     0  6.3G   0% /run/user/0

I have no VMs, or LXCs disks on local anymore, they are all on my ZFS volume now, so there a lot of unaccounted used space on /dev/mapper/pve-root.

bbgeek17 · 2025-10-25T01:40:53+0200

Hi @jgabrielpb , welcome to the forum.

You likely managed to dump data into one of the folders that is later being mounted over. See one of these links. There are many more if you search the forum.

Another option, is that you uploaded some large iso/qcow files and then removed them, but they are still open by some process and take space.
https://serverfault.com/questions/2...showing-correct-free-space-after-file-removal

R

Thread '/dev/mapper/pve-root is full'

Feb 2, 2023

Hello,

So I have used proxmox for 1 week now and I really enjoy it. But my disk for Proxmox is apparently full, and as I checked up on this, I can see, that /dev/mapper/pve-root is taking up all my space.

I have no experience in servers, i'm very new to this, so all help I can get is appreciated. See attached picture of the pve-root using 94Gb of space.

Thank you for your help.

[SOLVED] Post in thread 'Local storage /dev/mapper/pve-root full'

Mar 17, 2023

For others who will come across this later:

I suspect you marked it solved because you found that /mnt at 83G is the culprit due to data being located in root volume, rather than a disk which you thought was mounted?

Its always best to run "du" with -x option, that way it wont cross filesystem boundaries and will give you an accurate information about the specific parent mountpoint.

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

F

[SOLVED] Post in thread 'Full disk on VM but can't find files taking up space'

Sep 8, 2020

I've figured out my problem. I had mounted a CIF share to /mnt/my_cif_share/ but before mounting this folder already had 50GB of files in it. As far as I can tell mounting over it essentially 'hides' those files from du and similar tools.

To rectify, you can either unmount the share, and delete the 'hidden' files. Or to fix this without unmounting, you can remount your root folder using mount -o bind / /mnt and you will be able to delete the files from there.

[SOLVED] Post in thread 'Local (pve) unknown storage (VE 8.0)'

Nov 16, 2023

what is the output of: du -h -x -d1 /

Your usb is in /mnt/USB_backup , is there anything in /mnt besides that folder?

Also, unmount the USB disk - do you find anything in that folder still? If you written to the location while the disk was not mounted, it landed on root disk but will not be immediately seen.

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

Good luck

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

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Root filesystem (local) filling up on Proxmox host without visible files

jgabrielpb

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bbgeek17

Distinguished Member

Thread '/dev/mapper/pve-root is full'

[SOLVED] Post in thread 'Local storage /dev/mapper/pve-root full'

[SOLVED] Post in thread 'Full disk on VM but can't find files taking up space'

[SOLVED] Post in thread 'Local (pve) unknown storage (VE 8.0)'

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