proxmox ve: 無法備份vm, Permission denied

vm 備份時 出現訊息： 

INFO: starting new backup job: vzdump 209 --mode snapshot --compress zstd --remove 0 --storage local --node pve5
INFO: Starting Backup of VM 209 (qemu)
INFO: Backup started at 2021-02-01 13:12:25
INFO: status = running
ERROR: Backup of VM 209 failed - unable to open file '/etc/pve/nodes/pve5/qemu-server/209.conf.tmp.17505' - Permission denied
INFO: Failed at 2021-02-01 13:12:25
INFO: Backup job finished with errors
TASK ERROR: job errors

若是有 cluster, 可能是另一台 pve server 關機或出問題

在 pve server 中下指令即可：

$ pvecm expected 1

參考
http://blog.pulipuli.info/2014/03/proxmox-ve-cluster-repair-proxmox-ve.html