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.
Cephfs is great. It can be used to store and share files and can take advantage of the granularity and performance of Ceph. Big amounts of data can be stored and live snapshots can be taken so remote backups can be easily performed.
Sometimes servers can become unresponsive. Both physical and virtual, you may be unable to connect to them, especially when overloaded. So a watchdog can be a solution.