NAS recommendations for my purposes?

I've never had a NAS.

About half my data will be backups for Blu-rays, DVDs and 4K movies. I don't need two copies of the rips, since I have the discs, so that portion doesn't need a RAID.

The other huge portion is downloaded and other data I don't have hard copies of, that I do want two digital copies of. All of it is currently stored on three separate internal hard drives. I think I'm using all my SATA ports now, and my storage is about 70 percent full.

Could I keep both the files I need mirrored and the files I only want one copy of in the same folders? Would I just name the files differently and then program the NAS to only make copies of the files named a certain way or do I put them in separate folders? Would I use RAID 1 or 0?

This is what I'm thinking of getting:

https://www.amazon.com/dp/B07KMKDW42

Synology 8 Bay NAS (DS1819+)

I'll probably connect it to my computer with an Ethernet cable, if I'm able to use the same single one that I use for internet. But I'm wondering if it's overkill for my purposes. Something else you'd recommend?

For the hard drives, I think three WD Red 12 TBs will cover me for the next several years. They're 305 dollars each and made for RAIDs or to run continually.

@ezekiel43: Hell of a NAS storage unit, I'd go with raid 5.

Would never use raid 0 on a NAS, it completely destroys the idea of backup.

@gerygo: Didn't even understand RAID 5 until now. Sounds good. I can live with the capacity of all but one hard drive for my hard copies, considering that it would take days to rip, remux and name everything again after a failure. Now to decide if I wanna get it now or wait until Black Friday/Cyber Monday.

@ezekiel43: depends on how urgent the whole backup thing is for you, if it's not - then I'd wait for these sale days because you are buying 12Tb of dedicated storage HDDs so it'll save you some cash.

Actually, the discs (DVD/BD/UHD) will be the backups. The NAS will be how I access and watch them, bypassing all the piracy warnings and menus and sleeve packaging that can scratch discs by forcing the user to slide them in and out. I've filled up all my shelves and now have to put cases on top of each other and in front of each other. Eventually, I'm gonna have trouble finding discs at all. There's still plenty of time, though. I'll wait until November.

I have the Synology 1813+, an earlier version if the one you are looking at. I also have a DX513 which is a 5 drive expansion unit. Every bay on both is filled with between 4TB and 8TB drives. I'm running a hybrid RAID and my total usable capacity is about 40TB. Each device has a separate volume. The 8 drive device has 30TB running as a SAN which is presented as a lun to a file server, and the 10TB expansion is running as a NAS. Both volumes are sources for my Plex server.

I'd recommend Synology as a brand for home or small to medium sized business RAID solutions if you aren't running real server hardware. It's pretty versatile, their support is decent, and their devices are reliable.

RAID offers a lot of different options/levels depending on the what you need. Some levels offer redundancy, performance, or both. Each will have differing disk requirements and offer different levels of usable capacity. For what you're looking for, you'll probably want to go with Synology Hybrid RAID (SHR) which is a RAID option unique to their devices. It's similar to RAID 5 but it does a better job of making use of capacity if you are using drives of mismatched capacities. For your use case, even if you are streaming UHD content the more redundant levels of RAID 5 or SHR will be fast enough over gigabit ethernet.

Bear in mind, though, that RAID levels are not backup. They are redundancy, meaning that you won't lose your data over the failure of one or more drives (depending on redundancy level). Without an actual backup, you can still lose all your data in one event, depending on that nature of that event (malware, ransomware, or other forms of data corruption). RAID only protects against hardware failures. It's still a good idea, since the life of every drive is finite, but redundancy and backup at the same time are ideal.