Backup error - zfs error: cannot create snapshot dataset already exists

Thanks! the trace looks a bit like: https://github.com/openzfs/zfs/issues/16324
the zfs-issue was fixed, and the fix was pulled into ZFS 2.2.7 - this should be included in proxmox-kernel version 6.8.12-7 (and the last 6.11 kernel as well)

Could you update to the latest version (6.8.12-7 is available on pve-no-subscription), reboot and see if it fixes the issue?
 
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Well if there isnt any other way, i guess im gonna need to reboot server, thanks for help.
 
Well reboot helped, it kinda didnt want to unmount rpool because of this locked dataset, so i had to turn it off and back on. But when it got back up i could remove that vzdump dataset.
 
SoLoR said:
Well reboot helped, it kinda didnt want to unmount rpool because of this locked dataset, so i had to turn it off and back on. But when it got back up i could remove that vzdump dataset.
Click to expand...
I would expect that - hopefully the issue does not reoccur with the fix in zfs - if it does - please report back here with dmesg/journalctl output and pveversion -v

Thanks!
 
Hello, I have the same error using kernel 6.8.12-7-pve.

Bash: 
$ journalctl
Jun 06 02:02:33 b-prod pvescheduler[3705880]: INFO: Starting Backup of VM 119 (lxc)
Jun 06 02:02:53 b-prod kernel: overlayfs: fs on '/var/lib/docker/overlay2/l/5XHP4SB36XDUXOUXWUDSQJQWGZ' does not support file handles, falling back to xino=off.
Jun 06 02:02:58 b-prod pvescheduler[3705880]: snapshot 'vzdump' was not (fully) removed - zfs error: cannot destroy snapshot rpool/data/subvol-119-disk-0@vzdump: dataset is busy
Jun 06 02:02:58 b-prod pvescheduler[3705880]: INFO: Finished Backup of VM 119 (00:00:25)

$ pveversion -v
proxmox-ve: 8.4.0 (running kernel: 6.8.12-7-pve)
pve-manager: 8.4.1 (running version: 8.4.1/2a5fa54a8503f96d)
proxmox-kernel-helper: 8.1.1
proxmox-kernel-6.8: 6.8.12-9
proxmox-kernel-6.8.12-9-pve-signed: 6.8.12-9
proxmox-kernel-6.8.12-8-pve-signed: 6.8.12-8
proxmox-kernel-6.8.12-7-pve-signed: 6.8.12-7
proxmox-kernel-6.8.12-5-pve-signed: 6.8.12-5
proxmox-kernel-6.8.12-4-pve-signed: 6.8.12-4
proxmox-kernel-6.8.4-2-pve-signed: 6.8.4-2
ceph-fuse: 17.2.7-pve3
corosync: 3.1.9-pve1
criu: 3.17.1-2+deb12u1
glusterfs-client: 10.3-5
ifupdown2: 3.2.0-1+pmx11
ksm-control-daemon: 1.5-1
libjs-extjs: 7.0.0-5
libknet1: 1.30-pve2
libproxmox-acme-perl: 1.6.0
libproxmox-backup-qemu0: 1.5.1
libproxmox-rs-perl: 0.3.5
libpve-access-control: 8.2.2
libpve-apiclient-perl: 3.3.2
libpve-cluster-api-perl: 8.1.0
libpve-cluster-perl: 8.1.0
libpve-common-perl: 8.3.1
libpve-guest-common-perl: 5.2.2
libpve-http-server-perl: 5.2.2
libpve-network-perl: 0.11.2
libpve-rs-perl: 0.9.4
libpve-storage-perl: 8.3.6
libspice-server1: 0.15.1-1
lvm2: 2.03.16-2
lxc-pve: 6.0.0-1
lxcfs: 6.0.0-pve2
novnc-pve: 1.6.0-2
proxmox-backup-client: 3.4.1-1
proxmox-backup-file-restore: 3.4.1-1
proxmox-firewall: 0.7.1
proxmox-kernel-helper: 8.1.1
proxmox-mail-forward: 0.3.2
proxmox-mini-journalreader: 1.4.0
proxmox-offline-mirror-helper: 0.6.7
proxmox-widget-toolkit: 4.3.11
pve-cluster: 8.1.0
pve-container: 5.2.6
pve-docs: 8.4.0
pve-edk2-firmware: 4.2025.02-3
pve-esxi-import-tools: 0.7.4
pve-firewall: 5.1.1
pve-firmware: 3.15-4
pve-ha-manager: 4.0.7
pve-i18n: 3.4.4
pve-qemu-kvm: 9.2.0-5
pve-xtermjs: 5.5.0-2
qemu-server: 8.3.12
smartmontools: 7.3-pve1
spiceterm: 3.3.0
swtpm: 0.8.0+pve1
vncterm: 1.8.0
zfsutils-linux: 2.2.7-pve2
 
I just wanted to add that we have the same problem. It would be great if we could find a way to temporarily fix the error without rebooting the hypervisor all the time.

Code: 
118: 2025-06-25 02:02:40 ERROR: Backup of VM 118 failed - CT is locked (snapshot-delete)

$zfs destroy rpool/data/subvol-118-disk-0@vzdump
cannot destroy snapshot rpool/data/subvol-118-disk-0@vzdump: dataset is busy

$pveversion -v
proxmox-ve: 8.4.0 (running kernel: 6.8.12-8-pve)
pve-manager: 8.4.1 (running version: 8.4.1/2a5fa54a8503f96d)
proxmox-kernel-helper: 8.1.1
proxmox-kernel-6.8.12-11-pve-signed: 6.8.12-11
proxmox-kernel-6.8: 6.8.12-11
proxmox-kernel-6.8.12-9-pve-signed: 6.8.12-9
proxmox-kernel-6.8.12-8-pve-signed: 6.8.12-8
proxmox-kernel-6.8.12-4-pve-signed: 6.8.12-4
ceph-fuse: 17.2.7-pve3
corosync: 3.1.9-pve1
criu: 3.17.1-2+deb12u1
glusterfs-client: 10.3-5
ifupdown2: 3.2.0-1+pmx11
ksm-control-daemon: 1.5-1
libjs-extjs: 7.0.0-5
libknet1: 1.30-pve2
libproxmox-acme-perl: 1.6.0
libproxmox-backup-qemu0: 1.5.1
libproxmox-rs-perl: 0.3.5
libpve-access-control: 8.2.2
libpve-apiclient-perl: 3.3.2
libpve-cluster-api-perl: 8.1.1
libpve-cluster-perl: 8.1.1
libpve-common-perl: 8.3.1
libpve-guest-common-perl: 5.2.2
libpve-http-server-perl: 5.2.2
libpve-network-perl: 0.11.2
libpve-rs-perl: 0.9.4
libpve-storage-perl: 8.3.6
libspice-server1: 0.15.1-1
lvm2: 2.03.16-2
lxc-pve: 6.0.0-1
lxcfs: 6.0.0-pve2
novnc-pve: 1.6.0-2
proxmox-backup-client: 3.4.2-1
proxmox-backup-file-restore: 3.4.2-1
proxmox-firewall: 0.7.1
proxmox-kernel-helper: 8.1.1
proxmox-mail-forward: 0.3.3
proxmox-mini-journalreader: 1.5
proxmox-offline-mirror-helper: 0.6.7
proxmox-widget-toolkit: 4.3.11
pve-cluster: 8.1.1
pve-container: 5.2.6
pve-docs: 8.4.0
pve-edk2-firmware: 4.2025.02-3
pve-esxi-import-tools: 0.7.4
pve-firewall: 5.1.1
pve-firmware: 3.15-4
pve-ha-manager: 4.0.7
pve-i18n: 3.4.5
pve-qemu-kvm: 9.2.0-5
pve-xtermjs: 5.5.0-2
qemu-server: 8.3.13
smartmontools: 7.3-pve1
spiceterm: 3.3.0
swtpm: 0.8.0+pve1
vncterm: 1.8.0
zfsutils-linux: 2.2.7-pve2
 
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