On the question of OS, I thought Proxmox is going to be the Main OS of the system then (or did I understand that wrong?)
Proxmox is a virtualization distro. If you want to run VMs, you install Proxmox on the actual physical hardware, then install your VMs beneath Proxmox.
From what I know, RAID is great to have no downtime while upgrading/migrating/restoring; but as I’m not planning to do anything critical (just personal things like HAss, paperless, immich and my website), I think I can live without it and rather focus on having a simple backup solution.
You’re basically correct about RAID; more importantly, you’re correct that if you have to choose between RAID and backups, you choose backups every time.
- I’m planning to have a 2TB NVMe SSD as a main drive for the server, with some SATA HDD as a backup drive: Can I simply rsync the main drive to it in case it fails? Or what would be the way to go about doing this?
I’d strongly recommend using syncoid to handle replication. You’ll have both drives running ZFS, each as a single drive pool, and you’ll just automate replication between them. Replication is generally between one and three orders of magnitude faster than rsync, when it comes to virtual machine backups.
- On that note, should I even use a HDD for backing up since it’ll consume more power than an SSD, or can I power it down until it’s needed? I had issues with HDD power management in the past so it’s better to ask than to find out afterwards!
I do not recommend spinning HDDs up and down frequently. It puts a lot of additional wear and tear on multiple components, including bearings and coils, for very little real savings. (Standby power consumption on HDDs is typically around 1W; there are 61,320 hours per year, which means 1W is equivalent to about 61KWh–where I live, that in turn translates to about $8.50. You can likely save FAR more power by upgrading the insulation in your home, even something as simple as adding or replacing the “sweep” strips at the bottom of your external doors, or adding stick-on insulation strips around the frame. Then there are window treatments. Then upgrading older appliances. And we haven’t even talked about heating and cooling systems…)
I would definitely recommend a larger drive, if you want to use a SATA HDD. But for this small an amount of data, you might want to consider a SATA SSD instead. A 4TB SSD typically runs around $200, vs a 4TB HDD at around $100.
File systems: I feel like there are people saying ZFS is the best, full-stop, while others say it’s not great on SSD lifespan. So: What advice would you give me?
There’s no significant difference in SSD lifespan unless you’re doing something really unusual, like taking hundreds or thousands of snapshots per day in the least efficient way possible. Even then, it’s generally not enough to really matter much. I generally expect to get 5-7 years out of consumer SSDs on anything up to and including light server duty. (Servers that serve hundreds or thousands of people all day every day are a different story, and I’d be giving you somewhat different advice if you were asking about that.)