TheHolm

If you need something which can withstand some bitrot on single drive, just use par2. As long is filesystem is readable, you can recover files even if bit of data get corrupted

It means you published 8080. Just stop doing it. nginx can reach that container via internal network (assuming they are on same network). Publishing docker-compose would help.

Just a hdd in usb caddy? IMHO good enough for 4 tier backup.

just a normal PC? Streaming should work in a browser.

Just a folder + syncthing. no extra infra is necessary + easy to backup.

Get yourself some old cisco 3600 re-flash it with standalone firmware and get enterprise class WAP for cheap.

yes, is what i get reading about that server backplane. NVME part will need another "controller"

what is wrong with old good LSA 2008 based HBAs with SAS-to-Oculink cable? and for NVMe part, adapter is just port format converter, pick any.

ICINGA/NAGIOS? you can even feed data already collected by Prometheus to it if you want.

Ahh age of switching PSUs and led lights. 20 years ago you will notice it in an instant.

A4-6210 with build in GPU has TDP of 15W. There is no point to optimize anything it is seeping power already. may be try to use tlp to limit max charge level of the battery ( i'm not sure is you laptop is supported). You can play with governors too, but I personaly will not bother. You obviously need multiuser.target but not GUI.

With raid 10 - i would not risk it . With RAID6 ( obviously not on BTRFS) it is fair game if you have solid return policy for drives which are DOA. Go for SAS drives, they are cheaper (but generally hotter and nosier). And look for old-new-stock on specialized sites, no one in enterprise needs say 8tb drives, so they selling them cheap at times.

Get drive, connect , run long smart self-test ( for 18tb it is probably take a day). If it passed you are reasonably sure that it will not die soon. And keep running these test regularly, as soon as they start failing, replace.