Can I Share One PBS Instance Between Old and New Proxmox Servers?

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zikou

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Nov 13, 2024
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Hi all,


We currently have a Proxmox Backup Server (PBS) that is connected to our older Proxmox VE server and is used for scheduled VM backups.


We recently set up a new Proxmox VE server (we are not using cluster), and I would like to know:


  1. Can I attach the same PBS to this new Proxmox server while keeping it attached to the old one? The idea is to have both Proxmox servers backing up to the same PBS.
  2. If yes, how does PBS handle VM ID collisions? For example, if there is a VM with ID 107 on both the old and new Proxmox servers, will this cause conflicts on the PBS?

Any best practices or configuration advice would be greatly appreciated!


Thanks in advance.
 
Last edited:
I have a small side note:
_gabriel said:
( Datastore stay the same with data dedup over all Namespaces )
Click to expand...
Just make sure to use the same encryption key to achieve this. (Encryption is done on the client, the PVE, while de-duplication happens on PBS...)
 
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_gabriel said:
1/ Yes
2/ You can create a new Namespace on your PBS then add it to your New PVE.
( Datastore stay the same with data dedup over all Namespaces )
Click to expand...
so in the new proxmox
I put value of the pbs and namespace like Dev-ns, with that I will not have the issue VM ID collisions is that right?
1753040008603.png
 
zikou said:
so in the new proxmox
I put value of the pbs and namespace like Dev-ns, with that I will not have the issue VM ID collisions is that right?
View attachment 88219
Click to expand...

And you need to select the namespace after entering the Datastore, but that's it. It's a good idea to use a different API-Key for each namespace and backed up cluster so in case of an ransomware or hacker attack the bad actor can only mess around with a subset of your backups. You should also setup tight access rules so new backups can be added from your PVE-Cluster, but the removal is only possible from the PBS (via prune jobs or manually from the admin). Combined with a replication to a offsite PBS (configured as PULL sync, so a hacked local PBS only can add data but not remove or alter the older backups before the attack) this will ensure to limit the outreach of a security incident: https://pbs.proxmox.com/docs/storage.html#restrictive-user-access-management
 
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I attached the pbs to the new proxmox

1753093534081.png

when I tried to do a backup I got this
INFO: Starting backup: [Dev-ns]:ct/105/2025-07-21T10:18:49Z
INFO: Client name: ns3197579
INFO: Starting backup protocol: Mon Jul 21 10:18:52 2025
INFO: Error: namespace not found
ERROR: Backup of VM 105 failed - command 'lxc-usernsexec -m u:0:100000:65536 -m g:0:100000:65536 -- /usr/bin/proxmox-backup-client backup '--crypt-mode=none' pct.conf:/var/tmp/vzdumptmp358893_105/etc/vzdump/pct.conf root.pxar:/var/tmp/vzdumptmp358893_105 --include-dev /var/tmp/vzdumptmp358893_105/. --skip-lost-and-found '--exclude=/tmp/?*' '--exclude=/var/tmp/?*' '--exclude=/var/run/?*.pid' --backup-type ct --backup-id 105 --backup-time 1753093129 --entries-max 1048576 --repository root@pam@some-ip-address:backups --ns Dev-ns' failed: exit code 255
INFO: Failed at 2025-07-21 10:18:53
INFO: Backup job finished with errors
ERROR: could not notify via target `mail-to-root`: could not notify via endpoint(s): mail-to-root: no recipients provided for the mail, cannot send it.
TASK ERROR: job errors
 
On PBS: <your current datastore> --> Content --> top right Button "+ Add Namespace" :-)
 
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As @UdoB wrote, so it will work for you. I'm using this feature since it's for the Proxmox BS is available.
I can manage now different Proxmox VE Server on the Proxmox BS.
 
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