Selfhosted

I built my own and it honestly wasn't that expensive (at the time back in 2018). I just started with the basics but built it to be expandable. I used a Define 6 case which gave me room for 12 HDDs, a mobo with the highest number of SATA ports, processor, RAM, etc and then just added drives 1-2 at a time as they filled up. My only regret is that I didn't and still haven't learned Linux well enough to rely on it because it runs Windows, the PC is showing its age now, and I need to think about the replacement solution and how I'll be able to migrate 70+ TB of media and all my configurations to the new machine.

If you do run Windows, Drivepool and SnapRAID are useful for pooling everything into a single virtual disk and setting up a software RAID that will protect from drive failures without locking your data away.

You may not be able to do RAID or other redundant/performant arrays with USB. You can definitely achieve a big JBOD array but it will be less resilient and slower than a RAID array. Enclosures often don’t cool as well so heat may degrade your disks faster as well. I did this for a while with some old disks and some $30 HDD toasters. I only put data on there I could afford to lose. I wish there was a standalone hardware RAID solution… like a NAS without the network. That would have a huge draw for hobbyists that don’t want to buy an expensive NAS. I’ve searched for this but haven’t found anything. Message me if you know of such a product! Maybe consider building your own NAS with an old PC. Way cheaper than a prebuilt and fun to build! I had an old Dell Optiplex 990 that is now a 32 TB NAS. Had to get a new case but it’s a decent backup to my Synology.

I use an M1 Mac Mini running Asahi Linux with a USB 3.0 4-bay enclosure. Works great so far.

Yes, and you might want to ask in the datahoarders community.

While I dont use a mini-pc, I have a server with 48TB in it on spinning disks, and I've built a hybrid DAS/NAS that I back up to.

I use this 4-bay DAS: https://www.amazon.com/gp/aw/d/B078YQHWYW I chose it because it supports USB 3.2 Gen 2 and I've been pretty happy with it.

It's usually plugged into my server directly, and I use ZFS to snapshot and send to it. However, I also can plug it into a Pi5 and use ZFS send over SSH to treat it like a NAS. The Pi can of course run Samba/CIFS and SSH for sshfs.

The biggest downside to this structure is probably the metadata speeds for ZFS over USB (looking up snapshot names), but you could always use a cache drive with ZFS.

I highly, highly recommend ZFS and figuring out your software requirements before picking hardware.

Happy to answer any specific questions, too.

It's viable, but when you're buying a DAS for the drives, figure out what the USB chipset is and make sure it's not a flaky piece of crap.

Things have gotten better, but some random manufacturers are still using trash bridge chips and you'll be in for a bad time. (By which I mean your drives will vanish in the middle of a write, and corrupt themselves.)

Get a USB-C DAS (enclosure) for your disks, those use their own power supply. Since it is USB-C performance will be very good and stable and you'll be happy with it.

Get old HP thinclient T510, or Igel M340C. Got a few of those practically free online. Has Via Eden 1.2Ghz 2 core. Not powerful at all. But cold. Mine runs on hot summer days approximately between 40-50C. HP has I think 19V power source, Igel runs on 12V brick.

Consider the machine being on 24/7 and cooling.

Furthermore, depending on the current power supply, you might need to upgrade it to keep everything running.