Backup is not a tool. Backup is not a software you can buy. Backup is a strategy you need to study and implement to be able to solve your specific problems.
We started a complex, continuous and not always linear operation, that is to migrate, where possible, most of the servers from Linux to FreeBSD. Here's why.
If you are using Proxmox, ZFS is one of the best local storage options. You can easily backup your lxc containers using Borg.
Lxc containers are fast, small and useful. Proxmox Backup Server is quite slow with them, so here's how to perform a fast and efficient backup using Borg.
Proxmox Backup Server (PBS) has been released. It's still in beta but is already perfectly usable. After many years, it's now possible to perform incremental backups of the VMs and thanks to the qemu dirty bitmaps, backups are also fast.