I dived into the selfhosting rabbit hole once again and again I am stuck at the hardware part. I’d like to start small-ish to make it realisable. I thought about a NAS (Openmediavault probably). First I wanted to do it on a Raspberry Pi with an external hard-drive but then I read USB connected drives are unreliable and so on. Mini PCs are too small to house internal drives so should I go with a (refurbished) business PC from ebay and add some drives to it?But they usually come with Windows 10, which I wouldn’t need but makes them more expensive. I also have at least one old PC case laying around but no mainboard or CPU for it, if that info might be important. Thank you in advance for helping a noob out!
Edit: What I want to achieve: I would like a NAS and (separated) a server with some small services (pi-hole or adguard, syncthing, jellyfin (getting the data from the NAS), and so on). I thought about running the small services with docker on a RPi 4 and the NAS on a refurbished business PC with SATA drives in the case (I checked ebay and there are mainboards with 4 SATA III connectors and PCI so I could even add more SATA connectors). In a second moment a backup server (maybe with borg) would be a good idea but I could also do manual backups with an external USB HDD for the time being.
Yeah, try to avoid using USB hard drives.
A refurbished business PC is an excellent choice (or, better yet, make friends with someone who works in an IT department and grab a few machines when they’re being thrown out; you’d be amazed how often companies dump perfectly good hardware). Don’t worry about the windows license, you’re not actually paying for it by the time you get to refurb prices.
You should easily be able to pick up something decent for under $200 (hopefully that fits your budget). If you go with a small form factor (not ultra small) you can probably get an SSD and two 3.5" drives in there (watch out for the small form factor Lenovos though, they only have one 3.5" slot). Alternatively, look for a larger desktop tower style that could have 3 or 4 drive bays if you want to do something like a RAID5.
Don’t sweat too much about buying older hardware. What’s old and busted for Windows is lightning fast when we’re talking about self-hosting a file server or a Pihole.