PBS backups of arm64 guests failing

[leenooks]

Howdy,

Love the arm64 availability - I've got a CM5 cluster using a Super4C board and I'm building it as I speak. I went the "upgrade" from tixie path - everything appears to work well except its on the trixie kernel `Linux cm5-3-0 6.18.39+rpt-rpi-2712 #1 SMP PREEMPT Debian 1:6.18.39-1+rpt1 (2026-07-29) aarch64 GNU/Linux`, not the proxmox v7 kernel
Look forward to it being supported officially on these boards

Anyway, PBS backups are not working and I'm wondering if this is expected or something to do with how I've installed it. When I back up the first time, the backup succeeds. Any subsequent back fails with:

INFO: starting new backup job: vzdump 400 --node cm5-4-0 --storage pbs --remove 0 --mode snapshot --notes-template '{{guestname}}' --notification-mode notification-system
INFO: Starting Backup of VM 400 (qemu)
INFO: Backup started at 2026-08-31 07:49:31
INFO: status = running
INFO: VM Name: debian-12
INFO: include disk 'scsi0' 'zfs:vm-400-disk-1' 32G
INFO: include disk 'efidisk0' 'zfs:vm-400-disk-0' 64M
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: creating Proxmox Backup Server archive 'vm/400/2026-08-31T06:49:31Z'
INFO: issuing guest-agent 'fs-freeze' command
INFO: starting backup via QMP command
INFO: issuing guest-agent 'fs-thaw' command
ERROR: VM 400 qmp command 'backup' failed - backup register image failed: command error: no previous backup found, cannot do incremental backup
INFO: aborting backup job
INFO: resuming VM again
ERROR: Backup of VM 400 failed - VM 400 qmp command 'backup' failed - backup register image failed: command error: no previous backup found, cannot do incremental backup
INFO: Failed at 2026-08-31 07:49:32
INFO: Backup job finished with errors

A test restore of the original backup also fails:

new volume ID is 'zfs:vm-400-disk-0'
new volume ID is 'zfs:vm-400-disk-1'
restore proxmox backup image: /usr/bin/pbs-restore --repository root@pam@pbs-1-1.dege.internal:truenas_s3 vm/400/2026-08-31T06:34:14Z drive-efidisk0.img.fidx /dev/zvol/zfs/vm-400-disk-0 --verbose --format raw --skip-zero
connecting to repository 'root@pam@pbs-1-1.dege.internal:truenas_s3'
using up to 4 threads
open block backend for target '/dev/zvol/zfs/vm-400-disk-0'
starting to restore snapshot 'vm/400/2026-08-31T06:34:14Z'
download and verify backup index
restore failed: unable to read fixed index 'drive-efidisk0.img.fidx' - EINVAL: Invalid argument
temporary volume 'zfs:vm-400-disk-1' successfully removed
temporary volume 'zfs:vm-400-disk-0' successfully removed
error before or during data restore, some or all disks were not completely restored. VM 400 state is NOT cleaned up.
TASK ERROR: command '/usr/bin/pbs-restore --repository root@pam@pbs-1-1.dege.internal:truenas_s3 vm/400/2026-08-31T06:34:14Z drive-efidisk0.img.fidx /dev/zvol/zfs/vm-400-disk-0 --verbose --format raw --skip-zero' failed: exit code 255

In PBS, the backup verifies just fine

2026-08-31T16:56:13+10:00: verify truenas_s3:vm/400/2026-08-31T06:34:14Z
2026-08-31T16:56:13+10:00: check qemu-server.conf.blob
2026-08-31T16:56:13+10:00: check drive-scsi0.img.fidx
2026-08-31T16:57:47+10:00: verified 1837.71/6188.00 MiB in 93.54 seconds, speed 19.65/66.15 MiB/s (0 errors)
2026-08-31T16:57:47+10:00: check drive-efidisk0.img.fidx
2026-08-31T16:57:47+10:00: verified 0.00/4.00 MiB in 0.02 seconds, speed 0.09/184.17 MiB/s (0 errors)
2026-08-31T16:57:47+10:00: TASK OK

Any advice?

 

[leesteken]

Please try to reproduce this with the official Proxmox VE kernel. Also, please share the versions of Proxmox VE pveversion -v) and Backup Server that you are using. The system logs around the time of the backup attempts of PVE and PBS might also be helpful. (And please use CODE-block for terminal output).

 

[leenooks]

On the VE host:

proxmox-ve: 9.2.0 (running kernel: 6.18.39+rpt-rpi-2712)
pve-manager: 9.2.10 (running version: 9.2.10/43df2e01f27a1a19)
proxmox-kernel-helper: 9.2.0
proxmox-kernel-7.0: 7.0.14-14
proxmox-kernel-7.0.14-14-pve-signed: 7.0.14-14
proxmox-kernel-7.0.14-6-pve-signed: 7.0.14-6
ceph-fuse: 20.2.0-pve1
corosync: 3.1.10-pve3
criu: 4.1.1-1
frr-pythontools: 10.6.1-1+pve3
ifupdown2: 3.3.0-1+pmx12
libjs-extjs: 7.0.0-7
libproxmox-acme-perl: 1.7.2
libproxmox-backup-qemu0: 2.0.2
libproxmox-rs-perl: 0.4.1
libpve-access-control: 9.1.1
libpve-apiclient-perl: 3.4.2
libpve-cluster-api-perl: 9.1.6
libpve-cluster-perl: 9.1.6
libpve-common-perl: 9.2.1
libpve-guest-common-perl: 6.0.5
libpve-http-server-perl: 6.0.5
libpve-network-perl: 1.6.7
libpve-notify-perl: 9.1.6
libpve-rs-perl: 0.15.3
libpve-storage-perl: 9.1.7
libspice-server1: 0.15.2-1+b1
lvm2: 2.03.31-2+pmx1
lxc-pve: 7.0.0-2
lxcfs: 7.0.0-pve1
novnc-pve: 1.7.0-2
proxmox-backup-client: 4.2.4-1
proxmox-backup-file-restore: 4.2.4-1
proxmox-enterprise-support-keyring: 1.1
proxmox-firewall: 1.2.3
proxmox-kernel-helper: 9.2.0
proxmox-mail-forward: 1.0.3
proxmox-mini-journalreader: 1.7
proxmox-offline-mirror-helper: 0.7.4
proxmox-widget-toolkit: 5.2.7
pve-cluster: 9.1.6
pve-container: 6.1.13
pve-docs: 9.2.4
pve-edk2-firmware: not correctly installed
pve-firewall: 6.0.5
pve-firmware: 3.18-6
pve-ha-manager: 5.2.5
pve-i18n: 3.10.0
pve-qemu-kvm: 11.0.3-1
pve-xtermjs: 6.0.0-2
qemu-server: 9.2.4
smartmontools: 7.5-pve2
spiceterm: 3.4.2
swtpm: 0.8.0+pve3
vncterm: 1.9.2
zfsutils-linux: 2.4.4-pve1

On PBS:

root@pbs-1-1:~# dpkg -l |grep proxmox
ii  libproxmox-acme-plugins             1.7.2                                all          Proxmox acme.sh wrapper for DNS API plugins
ii  proxmox-archive-keyring             4.0                                  all          Proxmox APT archive keyring
ii  proxmox-backup                      4.2.0                                all          Proxmox Backup Server meta package
ii  proxmox-backup-client               4.2.5-1                              amd64        Proxmox Backup Client tools
ii  proxmox-backup-docs                 4.2.5-1                              all          Proxmox Backup Documentation
ii  proxmox-backup-server               4.2.5-1                              amd64        Proxmox Backup Server daemon with tools and GUI
ii  proxmox-default-kernel              2.1.0                                all          Default Proxmox Kernel Image
ii  proxmox-enterprise-support-keyring  1.1                                  all          Proxmox enterprise SSH support keyring
ii  proxmox-kernel-7.0                  7.0.14-12                            amd64        Latest Proxmox Kernel Image
ii  proxmox-kernel-7.0.0-3-pve-signed   7.0.0-3                              amd64        Proxmox Kernel Image (signed)
ii  proxmox-kernel-7.0.14-12-pve-signed 7.0.14-12                            amd64        Proxmox Kernel Image (signed)
ii  proxmox-kernel-7.0.14-4-pve-signed  7.0.14-4                             amd64        Proxmox Kernel Image (signed)
ii  proxmox-kernel-helper               9.2.0                                all          Function for various kernel maintenance tasks.
ii  proxmox-mail-forward                1.0.3                                amd64        Proxmox mail forward helper
ii  proxmox-mini-journalreader          1.7                                  amd64        Minimal systemd Journal Reader
ii  proxmox-offline-mirror-docs         0.7.4                                all          Proxmox offline repository mirror and subscription key manager
ii  proxmox-offline-mirror-helper       0.7.4                                amd64        Proxmox offline repository mirror and subscription key manager helper
ii  proxmox-termproxy                   2.1.0                                amd64        Wrapper proxy for executing programs in the system terminal
ii  proxmox-widget-toolkit              5.2.7                                all          Core Widgets and ExtJS Helper Classes for Proxmox Web UIs

The only thing the proxmox backup server log is this single line (around that time):
`Aug 31 16:49:32 pbs-1-1 proxmox-backup-proxy[1851283]: TASK ERROR: backup ended but finished state is not set.`

The VM host log is as I've shown above.