Error backing up a CT

H

Hardknight

New Member
Apr 3, 2026
6
0
1
Sunshine Coast Qld Australia
Hi All
Fairly new to Proxmox ;)
Trying to create a BU of a CT and keep getting this response

"ERROR: Backup of VM 101 failed - command 'set -o pipefail && lxc-usernsexec -m u:0:100000:65536 -m g:0:100000:65536 -- tar cpf - --totals --one-file-system -p --sparse --numeric-owner --acls --xattrs '--xattrs-include=user.*' '--xattrs-include=security.capability' '--warning=no-file-ignored' '--warning=no-xattr-write' --one-file-system '--warning=no-file-ignored' '--directory=/mnt/pve/sg-pbu/dump/vzdump-lxc-101-2026_05_12-11_28_17.tmp' ./etc/vzdump/pct.conf ./etc/vzdump/pct.fw '--directory=/mnt/vzsnap0' --no-anchored '--exclude=lost+found' --anchored '--exclude=./tmp/?*' '--exclude=./var/tmp/?*' '--exclude=./var/run/?*.pid' ./ .nx-data | zstd '--threads=1' >/mnt/pve/sg-pbu/dump/vzdump-lxc-101-2026_05_12-11_28_17.tar.dat' failed: exit code 2"

The CT is unlocked

Code: 
INFO: starting new backup job: vzdump 101 --remove 0 --node NFS --notification-mode notification-system --compress zstd --mode snapshot --notes-template NxWitness --storage sg-pbu
INFO: Starting Backup of VM 101 (lxc)
INFO: Backup started at 2026-05-12 11:28:18
INFO: status = running
INFO: CT Name: nxwitness
INFO: including mount point rootfs ('/') in backup
INFO: including mount point mp101 ('nx-data') in backup
INFO: found old vzdump snapshot (force removal)
  Logical volume "snap_vm-101-disk-0_vzdump" successfully removed.
  Logical volume "snap_vm-101-disk-0_vzdump" successfully removed.
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: suspend vm to make snapshot
INFO: create storage snapshot 'vzdump'
  Logical volume "snap_vm-101-disk-0_vzdump" created.
  WARNING: You have not turned on protection against thin pools running out of space.
  WARNING: Set activation/thin_pool_autoextend_threshold below 100 to trigger automatic extension of thin pools before they get full.
  Logical volume "snap_vm-101-disk-0_vzdump" created.
  WARNING: Sum of all thin volume sizes (<3.91 TiB) exceeds the size of thin pool cctv/cctv and the size of whole volume group (<3.64 TiB).
INFO: resume vm
INFO: guest is online again after 1 seconds
INFO: creating vzdump archive '/mnt/pve/sg-pbu/dump/vzdump-lxc-101-2026_05_12-11_28_17.tar.zst'
INFO: tar: .nx-data: Cannot stat: No such file or directory
INFO: Total bytes written: 2495119360 (2.4GiB, 146MiB/s)
INFO: tar: Exiting with failure status due to previous errors
umount: /mnt/vzsnap0nx-data: no mount point specified.
command 'umount -l -d /mnt/vzsnap0nx-data' failed: exit code 32
ERROR: Backup of VM 101 failed - command 'set -o pipefail && lxc-usernsexec -m u:0:100000:65536 -m g:0:100000:65536 -- tar cpf - --totals --one-file-system -p --sparse --numeric-owner --acls --xattrs '--xattrs-include=user.*' '--xattrs-include=security.capability' '--warning=no-file-ignored' '--warning=no-xattr-write' --one-file-system '--warning=no-file-ignored' '--directory=/mnt/pve/sg-pbu/dump/vzdump-lxc-101-2026_05_12-11_28_17.tmp' ./etc/vzdump/pct.conf ./etc/vzdump/pct.fw '--directory=/mnt/vzsnap0' --no-anchored '--exclude=lost+found' --anchored '--exclude=./tmp/?*' '--exclude=./var/tmp/?*' '--exclude=./var/run/?*.pid' ./ .nx-data | zstd '--threads=1' >/mnt/pve/sg-pbu/dump/vzdump-lxc-101-2026_05_12-11_28_17.tar.dat' failed: exit code 2
INFO: Failed at 2026-05-12 11:28:36
INFO: Backup job finished with errors
INFO: notified via target `mail-to-root`
TASK ERROR: job errors

Any guidance would be much appreciated
Thx in Advance
 
Hi,
please share the container config, you can obtain it via pct config 101. Most likely your mountpoint for nx-data is not configured correctly (relative vs. absolute path).
 
Hi Chris
Thx for the reply ;)

Code: 
root@NFS:~# pct config 101
arch: amd64
cores: 2

dev0: /dev/dri/renderD128,gid=993
dev1: /dev/dri/card1,gid=44
features: nesting=1,keyctl=1,mount=nfs;cifs;ext4
hostname: nxwitness
memory: 2048
mp101: cctv:vm-101-disk-0,mp=nx-data,backup=1,size=1000G
mp3: sg-pbu:101/vm-101-disk-0.raw,mp=/nx-bu,backup=1,size=100G
nameserver: 192.168.1.1
net0: name=eth0,bridge=vmbr0,gw=192.168.1.1,hwaddr=BC:24:11:37:E4:2D,ip=192.168.1.101/24,type=veth
onboot: 1
ostype: ubuntu
parent: vzdump
rootfs: SSD-2:vm-101-disk-0,size=8G
swap: 512
tags: nx-witness
timezone: Australia/Brisbane
unprivileged: 1

I added MP3 to see if the system would back up to this MP with no luck
MP101 is the video storage for cameras
I need a replica of the system including mac address and system ID for the camera licenses

Any guidance is appreciated
Thx H
 
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