Q: Proxmox Backup Server and "USB Drive" Set for offsite rotation ?


Renowned Member
Jun 4, 2008
Hi, I am curious to ask. This maybe super obvious but I am having trouble getting my head around it.

I've got a client who has onsite Proxmox system / which has PBS running locally on Proxmox Server as well. They have one main VM for their office to be operational. It has a nightly backup (~7pm) from Proxmox into the local PBS datastore / various retention and pruning / works nicely.

Then nightly (~9pm) there is a sync job with an offsite PBS server that pulls PBS data and gets an offsite copy of the onsite PBS Backup.

This seems to work "just perfectly" and is lovely. However, client is accustomed to having an onsite server and manual / daily ritual of USB drives that go offsite, as a way to be happy and confident that they've got a copy of data backups in their hands, offsite, in case of disasters etc. Arguably this is not a bad thing, although I feel maybe it is redundant given how smooth the offsite PBS backup method seems to be working.

That being said. I see that ProxmoxBackupServer has well integrated function for "TAPE BACKUP SUPPORT" as removable media for offsite backup storage.

I am wondering? if there is a way that I can basically setup using the 'tape backup' features - an offsite backup pool which is in fact not using LTO tape, but rather just a pair of USB disks which are manually rotated/connected to the Proxmox-PBS server.

ie, it seems to me that virtually all of what I seek must exist in the "PBS Tape Feature Set". But that it makes assumptions (I think) about using a special UserSpace RUST tape access implementation for dumping data to tape. Which strictly speaking is not really what I want. So much as the same basic logic "as if I had a manual LTO tape changer" and then a human will simply unplug/plug/rotate USB drives intermittently. And PBS "tape" config might have an entity called 'USB_HDD' which is not really a tape, so much as a block device which PBS has full control of. And for example a pool of (maybe, in this case) we define 2 'usb-drive-pseudo-tapes' as members of the rotation-pool.

And then the desired logic might be as simple as

PBS Local job runs at 7pm
PBS offsite sync runs at 9pm
PBS local sync-to-USB makes sure the local-USB-attached drive has a "Current copy of today VM Backup" plus possibly some trim-prune automation so we don't fill the 1Tb USB drive.

(In this case, the production VM is a 500gig VM / with about 200gb of actual footprint.content presently, and a nightly delta that is pretty tiny - on the order of 5gig or less)

End of the day, I am not fixated on the idea of using the 'tape features' to get this working. So much as it seems likely it could? be the most elegant and graceful way to do this.

I have a feeling I can probably kludge something, but not nearly as gracefully, with some simple cron jobs.

For example

Cron job runs at midnight.
Delete anything on USB drive if the drive is present
Dump a full VM backup onto the USB drive. Nothing to do with PBS or zpool dedup etc etc. Just a boring old reliable dump of VM.
then it generates a full VM dump onto USB. This probably takes a few hours since ~200-250gig footprint approx, and we have zero blocks reused / full dump each night
but at least it works, it is easy, and if the folks at the office rotate the USB offsite on a timeline they are happy with, they can always be assured of having
one offsite USB with 'last night' backup in their hands.


Any feedback is greatly appreciated.


usb disk as ext4 as pbs datastore then pull from pbs server.
then crontab to stop pbs then umount the disk then restart pbs.
Last edited:
usb disk as ext4 as pbs datastore then pull from pbs server.
then crontab to stop pbs then umount the disk then restart pbs.
As gabriel said, you can format your USB disk with another PBS datastore and configure a sync job from your 'normal' datastore to the USB datastore. You can even set up a group filter so that only a select set of VM-IDs get copied to the USB disk.

Something a lot of people miss is that a sync job can also be configured from local to local datastore, you just need to configure the Source Remote Host with 'localhost' instead of the FQDN or IP-Address, and his own Fingerprint.
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What kind of system did the thread starter end up with, apparently improvements are coming for the use of external disks in offsite backups, there is a mention in the pbs roadmap

(tape-like) syncing to S3/Object storage types

What does this mean, could any developer tell me about this, what kind of improvements
is coming to the use of external hard drives, for offsite backups


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