Backups take very long, are deltas only stored but also transferred?

[exp]

I just got to set up PBS for my small proxmox cluster. PBS runs on an older Intel Atom on GBe.

Backups take forever. Even when I run a backup back-to-back, the second runs takes again 30-60min. It seems to me that not only changes are transferred but the whole VMs/CTs.

Is this my right understanding?

I know that Intel Atom is not the most performant machine but meanwhile ZFS snapshots breeze through as expected from the same cluster nodes to the same PBS.


If a backup indeed does transfer the entire machine to PBS first (before deciding which data to store), is there a way to use zfs send instead?

Also, why does proxmox not just use ZFS snapshots/send? While I understand that the system should not depend too much on a specific file system, there could be the option; particularly since ZFS provides such powerful features and many (most?) people are using ZFS anyway

 

[Chris]

I just got to set up PBS for my small proxmox cluster. PBS runs on an older Intel Atom on GBe.

Your performance will be limited by compute power. For minimal recommended hardware see https://pbs.proxmox.com/docs/installation.html#minimum-server-requirements-for-evaluation

Backups take forever. Even when I run a backup back-to-back, the second runs takes again 30-60min. It seems to me that not only changes are transferred but the whole VMs/CTs.

Is this my right understanding?

This depends, VM backups will be incremental if the VM was not stopped in-between backup runs, only re-uploading changed or new data in that case. Same is true for CT backups, but normally the whole filesystem is read and chunked again on the source side if you are not using the change detection mode metadata, see https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_ct_change_detection_mode

I know that Intel Atom is not the most performant machine but meanwhile ZFS snapshots breeze through as expected from the same cluster nodes to the same PBS.


If a backup indeed does transfer the entire machine to PBS first (before deciding which data to store), is there a way to use zfs send instead?

You can of course relay on ZFS send/recieve, but this is not part of the PBS implementation and you will have to use your own tooling for that.

Also, why does proxmox not just use ZFS snapshots/send? While I understand that the system should not depend too much on a specific file system, there could be the option; particularly since ZFS provides such powerful features and many (most?) people are using ZFS anyway

The PBS implementation is not only agnostic to the filesystem used, but also more flexible when it comes to pruning, zfs snapshots are inter-dependent while backup snapshots in PBS are all self contained. That might be just one point, but there is no plan to implement such filesystem dependent features.