ominous ocelot

I would get some cheap maybe even used X86 hardware to start with. Depending on your backup needs, you might need more than one M2 or SATA port. If you plan to use it as an always on device, I would keep the power consumption in mind. A celeron N could be the way. The cpu processing power is, in my experience, not the limiting factor for a self-hosted environment. Give it lots of RAM, every virtual machine and every running service needs space.

Using arm, like a Raspberry Pi, is not bad if you can find all your Docker images and binaries, compiled for this platform. I went away from it.

There are many possible distributions and software you could use, it really depends on personal preference.

You can never be sure. Regressions do happen.

First evaluate it on your test setup.
— useless hint of the day

Some fs can do snapshotting (btrfs, zfs,…). Second best would be a current backup to restore from.

rsnapshot is a script for the purpose of repeatedly creating deduplicated copies (hardlinks) for one or more directories. You can chose how many hourly, daily, weekly,… copies you’d like to keep and it removes outdated copies automatically. It wraps rsync and ssh (public key auth) which need to be configured before.

• journalctl shows the oom event
• Container limits you can limit container resource usage
• also you can look at container stats to maybe identify the culprit. Or cyclically write the stdout of ps to a file to identify the memory hungry process.

Debian + LVM + Incus :)

The h4 already can be a managed switch itself (2" 2,5gbit + 4*1gbit with the nic addon.) if you want it to be one. Linux as the host OS (VLANs, bridges) - netplan works well for me. Some VMs and containers on top (lxd, incus, some use proxmox) for router/ firewall/ vpn-gateway (opnsense, ipfire,…) and other functionality which you don’t want to run on the host OS directly. The cpu is fast enough to run all your services at once. It all comes down to RAM.

IMO there is not one right way. It all depends on what you want to achieve. Also a lot depends on, whether you want results fast or if you enjoy the tinkering while learning.