Backups fail to Windows SMB share

[007bond007]

Hello,

I'm running Proxmox 7 virtual environment and on top running Proxmox Backup Server 2.3-1. I'm trying to backup a container on the virtual environment to PBS but having no luck. Please see the error in the backup log below.

Backup log:

()
2022-12-31T13:49:11-05:00: starting new backup on datastore 'VeeamDrive2': "ct/105/2022-12-31T18:49:10Z"
2022-12-31T13:49:11-05:00: protocol upgrade done
2022-12-31T13:49:11-05:00: GET /previous_backup_time
2022-12-31T13:49:11-05:00: POST /blob
2022-12-31T13:49:46-05:00: POST /blob: 400 Bad Request: fchmod "/media/backup-veeam/ct/105/2022-12-31T18:49:10Z/pct.conf.tmp_vpfcci" failed: EPERM: Operation not permitted
2022-12-31T13:49:46-05:00: backup failed: connection error: not connected
2022-12-31T13:49:46-05:00: removing failed backup
2022-12-31T13:49:46-05:00: TASK ERROR: connection error: not connected

The datastore is setup on PBS to a windows 10 box on an external drive. I've created a user specifically for this connection with "Full access" rights and even tried "Everyone" and "Anonymous" full access as a test. The PBS machine is an LXC with a pass-through SMB share from the host. Here's the fstab entry on the host:

//10.0.0.67/SharedBackup/ /media/backup-veeam cifs _netdev,x-systemd.automount,noatime,noforceuid,noforcegid,uid=100000,gid=110000,dir_mode=0770,file_mode=0770,user=veeam,pass=@password 0 0

Here is the PBS LXC configuration for the share access:

arch: amd64
cores: 4
features: nesting=1
hostname: HOME1PBS
memory: 2048
mp0: /media/backup-veeam,mp=/media/backup-veeam
net0: name=eth0,bridge=vmbr0,firewall=1,gw=10.0.0.1,hwaddr=9E:08:7B:9B:69:68,ip=10.0.0.78/24,tag=1,type=veth
ostype: debian
rootfs: NAS-LVM:vm-110-disk-0,size=32G
swap: 2048
unprivileged: 1

Any help is greatly appreciated - I've been searching and troubleshooting for days with no success.

 

[Dunuin]

You got 770 rights, so only UID 100000 should be able to access it. PBS uses different users for the datastore. For example UID 0 (root user), UID 34 (backup user) and unprivileged LXCs will also use UID 100000 on the PVE side. Try if it works with 777 rights.

 

[007bond007]

Hi Dunion.

I changed the mount line: dir_mode=0770,file_mode=0770 to dir_mode=0777,file_mode=0777 and did mount -a on the host, restarted the LXC and ran the backup again - same result. That does make sense though, you may be onto something there.

I have a group I created called LXC_Shares on the PBS LXC with GUID of 10000 with root and backup as members (I believe I had to add backup to this group for it to allow me to even add the datastore).

 

[Dunuin]

Also keep in mind that unprivileged LXCs can't mount any SMB/NFS shares. Only privileged LXCs can do that any only after enabling that feature in the LXCs options.

 

[007bond007]

Also keep in mind that unprivileged LXCs can't mount any SMB/NFS shares. Only privileged LXCs can do that any only after enabling that feature in the LXCs options.

Yes, it's mapped on the proxmox virtualization host and passed through via mp0 in the LXC configuration. Ok so managed to get the permissions to be 777 (had to unmount the share on the host and re-mount, mount -a didn't work on its own). Backup still fails!