Backup on encrypted external USB Disk - incremental Backup of VM and Files via PBS?

[AlpsView]

Hi all

me: proxmox newbie, medium linuxer, long time virtualisation experience with hyper-v. So coming from the darkside ;-)

Setup

• Proxmox with a couple of VMs
• VMs are stored on a local NVMe Disk
• An external 4 bay hdd storage connected via USB 3.0.
• One VM is a OMV server and all 4 (luks encrypted) external disks are passed through to OMV. The unlocking of the luks disks happens (manually) on OMV.
• These disks are used as file/media storage, filesystem ext4.
• No RAID, all single disks -> home setup. It's a trade off and i feel okay with it as long as i have a working and efficient backup. Data/media files is also backed up to a cloud storage using restic.
• One additional external USB 3.0 disk I'd like to use for Backups of VMs and Data (referenced as Backup-Disk).

Goal: I would like to create differential backups of my VMs and my file/media data to the "Backup-Disk".

(Incomplete and pot. atm inconsistent) Solution approach:

1. Mount the Backup-Disk to PVE
2. Encrypt the disk with luks. Did i get it right and there is no interface on PVE for unlocking? So it would have to happen on the console unless i add keyfile-based auto-unlocking?
3. Filesystem: Not sure which one would work best. I guess ext4 for an external Backup Disk would be a good choice at it could be mounted on almost every other linux system if needed. But I'm willing to learn what would be best in this case.
4. Creating a "Backup-Directory" on the "Backup-Disk" in PVE
5. Set up a PBS VM.
6. Mount the "Backup-Directory" on the PBS VM.
   I was first thinking about using disk pass through of the Backup-Disk to PBS instead. However, if i correclty understand, mouting it on PVE might allow the Backup-Directory to be shared with other VMs if needed, in case it shouldn't be possible to cover all backup needs (see question below) with PBS.
7. Set up a snapshot based incremental Backup-Job for the VMs system disks only in PBS, having PBS using the "Backup-Disk" to write to.

Questions:

• Does this make sense so far? Anything i missed? A better suitable approach?
• With only the system disk of PBS backed up, will PBS be able to backup its own VM? I think I remeber I read "yes", just asking to be sure I got this right.
• Is it possible to also use PBS to do incremental backups of my files/media storage? Just like with window's wbadmin? As the related disks are passed through to OMV (no virtual disk!), PBS would have to access/fetch these files/media via the related SMB share. Does PBS has this kind of functionality or do I have to go with another solution for the data/media backup?

I'm sure there are going to be more questions I might not yet see. So I'd like to check if I'm thinking into the right direction at all before starting into the wrong direction.

Any feedback is appreciated!

 

[leesteken]

Both Proxmox VE (PVE) and PBS do not support incremental/differential backups. PBS does do deduplication automatically by simply not storing duplicated data blocks more than once. I know PBS (when running as a container on PVE) can backup itself in snapshot mode (without the data storage) as I use that myself (and are very happy with it). There is also a specialized sub-forum about PBS: https://forum.proxmox.com/forums/proxmox-backup-installation-and-configuration.24/ . But I think you might need to find some third-party backup software that can do what you want.

 

[AlpsView]

Both Proxmox VE (PVE) and PBS do not support incremental/differential backups. PBS does do deduplication automatically by simply not storing duplicated data blocks more than once. I know PBS (when running as a container on PVE) can backup itself in snapshot mode (without the data storage) as I use that myself (and are very happy with it). There is also a specialized sub-forum about PBS: https://forum.proxmox.com/forums/proxmox-backup-installation-and-configuration.24/ . But I think you might need to find some third-party backup software that can do what you want.

Thanks a lot @leesteken

I think I understand. Although with PBS I could keep the backup runs i.e. from the last 8d, 4w, 12m and restore any of this, unlike a inc/diff backup like i.e. wbadmin backup on windows, I wouldn't be able to pick out a specific file, search for the dates it has been changed and restore the one i want. Which is because of PBS is working below file system level. So i does not handle changes in files but in data chunks. Which might be the same content in the end, but a different kind of access to it. Meaning, with PBS I would have to know in advance which date i would like to restore and then i would have to restore the whole backup, not only a specific file. Other than that, because of the deduplication in PBS I still would benefit from (far) smaller backups as only differences (based on chunks, not files) are written.
I have to think about this. For VMs OS disk I think that's perfectly suitable. For files backup I don't really like it. Restic i.e. also does dedupilication but works on file level. However it also does not provide the classical diff/inc backup but it seems to be closer to it than PBS.

As you suggested, it seems for data i might need a third party solution. Coming from windows that's a bit a pity as in windows there was a simple but effective backup solution covering both scenarios. Would be great to have something similar in PBS aswell.