Thanks very much for your answers, I appreciate it. I've put a couple comments/questions in your attached post.@Quozlator
No, you have not wasted your time and money.
I've gone back over this thread and if I summarise your needs correctly:
1. Keep your data convenient and available.
2. Sufficient performance for 2 4K TVs locally streaming. (You don't mention the bandwidth of the files - some "sourced" 4K films can be 60GB or more and need 100mbps easy, most streaming services use significantly lower bandwidth.) I have a large collection of DVDs that I want to be able to access from something like Plex or Jellyfin, so I was going to try ripping them myself. and friends may want me to "backup theirs" as well,
For #1 and #2, NAS is a good solution:
- You get all your data in one place and it stays available through a number of failure scenarios - it's true not all, but given things that typically fail on a well built machine, the HDD is the one with the moving parts and highest risk of failure. A NAS (generally) keeps your data available and accessible even if you have that HDD failure.
- Performance wise, you'll get the benefits you want and it will easily cover the ask you have.
For #3, as several of us have said, NAS is helpful but not the answer. What NAS does do though is significantly reduce the chance you will need to use that proper backup. It also reduces your effort if you do have a disk failure - and more importantly it keeps the wifes photos available to her while you fix the technology failure!
Like a good insurance policy, you want the backup to work but you don't want to have to use it. Replacing a single failed disk in a NAS and letting it re-sync is a pretty trivial exercise and provided the PC is powered on your wife has access to her photos whether the RAID is missing a disk, re-syncing in recovery or fully synced. So even if I have a failed disk in the NAS she can access it? Do you mean she can access from her computer and a copy there, or from the NAS itself? I was under the impression that the NAS would be useless until such time as I has replaced the defective disk and it has a chance to rebuild A full backup restore however is a far different beast - no data available until it's all restored including the time for you to source the disk.
The point about sourcing from different suppliers is helpful but not the end of the world. All of these things are about one thing: Risk reduction. Sourcing from multiple suppliers adds another level of protection in the (possible but unlikely) scenario the manufacturer had issues with a single production batch or the retailer accidentally left the pallet of disks next to an industrial magnet.
The advice you're getting is from technical experts that work in this stuff daily - these additional risk reduction points are important to them and their clients. At the end of the day though you're building a consumer solution with consumer parts at consumer cost. I did the same and am happy with the NAS system running. I'm sure you will be too.