Restoring backup on another system does not work

Hi all

Running PVE v 8.4.19, I want to upgrade to V9 and replace the disk so I created a backup from 1 LXC and offloaded it with SCP.
Moving the 3 files to my previous server with a fresh install, first 9.1, later 8.4.0
This keeps going wrong, whatever I do and I don't understand why.
The SSD I'm restoring to is 500GB and still has space since only OS is installed.

While restoring I keep getting a lot of "Cannot mkdir: No space left on device" errors.

Code:

df -h
Filesystem            Size  Used Avail Use% Mounted on
udev                  7.8G     0  7.8G   0% /dev
tmpfs                 1.6G  1.3M  1.6G   1% /run
/dev/mapper/pve-root   94G   18G   72G  20% /
tmpfs                 7.8G   46M  7.8G   1% /dev/shm
tmpfs                 5.0M     0  5.0M   0% /run/lock
/dev/fuse             128M   16K  128M   1% /etc/pve
tmpfs                 1.6G     0  1.6G   0% /run/user/0

This doesn't make sense to me.

My main setup is configured as ZFS, now I just left EXT4.
Is this the reason or what am I missing?

Thanks in advance!

Last edited: May 31, 2026

Hi Peter,
can you elaborate a little bit on the commands and results of your steps?

And also some interesting information to understand your issue can be provided by

Code:

lsblk;
cat /etc/pve/storage.cfg

BR, Lucas

Hi Lucas, thanks for helping!

I guess I'm list in this storage principle ZFS vs LVM and I choose ZFS (not used ever before) because of it's advantages.

Code:

lsblk
NAME                 MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda                    8:0    0 465.8G  0 disk
├─sda1                 8:1    0  1007K  0 part
├─sda2                 8:2    0     1G  0 part
└─sda3                 8:3    0 464.8G  0 part
  ├─pve-swap         252:0    0     8G  0 lvm  [SWAP]
  ├─pve-root         252:1    0    96G  0 lvm  /
  ├─pve-data_tmeta   252:2    0   3.4G  0 lvm 
  │ └─pve-data-tpool 252:4    0 337.9G  0 lvm 
  │   └─pve-data     252:5    0 337.9G  1 lvm 
  └─pve-data_tdata   252:3    0 337.9G  0 lvm 
    └─pve-data-tpool 252:4    0 337.9G  0 lvm 
      └─pve-data     252:5    0 337.9G  1 lvm

Code:

cat /etc/pve/storage.cfg
dir: local
        path /var/lib/vz
        content iso,vztmpl,backup

lvmthin: local-lvm
        thinpool data
        vgname pve
        content rootdir,images

The tar: Cannot mkdir: No space left on device error during a Proxmox LXC restore means the newly allocated root disk size is smaller than the uncompressed data inside your backup file. This commonly happens if the container originally used ZFS storage with compression enabled (making the data look smaller than it actually is) and you are now restoring it onto an uncompressed storage pool like LVM

i think its very old error

Fix 1: Force a Larger Disk Size via CLI You cannot change the target disk size from the Proxmox Web GUI during a restore. You must use the Proxmox Command Line interface (CLI) to override the root storage volume size.Log into your Proxmox host via SSH or use the host Shell in the web interface.Run the pct restore command, manually specifying a larger target size for the root file system (--rootfs):

pct restore <NEW_CT_ID> /path/to/backup/vzdump-lxc-xxx.tar.zst --storage <TARGET_STORAGE> --rootfs volume=<TARGET_STORAGE>:<SIZE_IN_GB>

also see

https://forum.proxmox.com/threads/lxc-restore-no-space-left-on-device.82139/

Last edited: May 31, 2026

Hi, thanks for that clue: it was a matter of restoring a backup taken from a ZFS filesystem to EXT4.
Because this was just a temporary/test system I started over with ZFS.

Thanks for your help!

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