so i was wonder i have a 3tb hard drive that’s almost full on my pc and 80% is stuff i almost never access but need too keep, so my question is can i just get an external drive bay (looking at a 5 bay docking station on amazon usb 3.1 gen 2 10Gb/s with power switches for each drive ) put an 8tb drive in it and just leave it off unplugged until i need it and just turn it on or will that corrupt the data eventually? or kill drives? Do i need to keep it in something running like a NAS and maybe put it in a RAID (i have just been googling RAIDs and NAS knowledge is close to nothing and i guess raid 5 would be best since 1 drive can fail outright)? It’s just stuff i wanna keep but don’t know the best way to store it and free up space on my pc.
Your solution should work fine. Hard disks (spinning) dont rot when powered down and a USB dock should be seamless. Just be careful not to go too cheap and get one with either a weak power supply or artificial capacity caps (some used ones will be limited to 2TiB.
As for your idea of a NAS, you are welcome to join the club any time, we are big NAS fans here on L1. The question always with network storage is your use case, never hardware.
If all you want is cold backup, you dont need a NAS. For resilience you dont need RAID, you just need multiple hard drives and rotate them. Use either a leapfrog model of 1,2,1,2 or a 3 disk rotation. There are solutions that let you do incremental daily backups but that requires planning and increases wear on the disk.
If you want to share data only with a couple of machines, such as a laptop and a desktop, then a network attached hard disk is a good cheap option. A WD MyCloud is the most common type, but other brands are available, and you can pick them up anywhere. Rules above apply on backup. You can get 2 disk versions of these and do a mirror. These are low power devices so are cheap to run and are designed to be always on.
If you want to “go big” then a consumer grade NAS gives you more options, and most have media streaming tools as well as a web interface that lets you schedule backups etc. This is the first and only time you should think about multidisk raid, like RAID 5. The use case for raid in 2020 is no longer about capacity (just buy a massive disk) or speed (use SSDs), but about Uptime. If you intend to run your NAS 24 hours a day and dont want to lose time restoring from backup, then Raid 5, 6 or 10 are options. If your data is more tolerant and a recovery from backup is no drama, then stick to a single disk or 2 disk mirror.
The other advantage of a network attached NAS is it moves the drives away from your PC (ie into a closet perhaps) and makes your workspace cleaner.
There is no wrong answer here and you wont waste money trying any option, but remember the disk is basically a commodity and will fail, so you need to budget for backups and build a process to keep at least 2 copies in separate locations at all times. This usually means at least 3 disks of a size large enough to store everything you need.
Final point - Hard disk prices dont scale linearly. It is always better to buy 2 big disks and mirror them than 3 or 4 smaller ones and use complex raid like RAID 5.
Edit: What Airstipone said, but I was too lazy to write out.
I think the central question to be answered is: does my sata disappear if I let my drive stay unplugged for prolonged periodes. Right? https://blog.macsales.com/43702-we-bet-you-didnt-know-that-your-hdds-or-ssds-may-need-exercise-too/
If you are planning only one HDD maybe think of Odroid HC2 / HC1. Then you can make a NAS based on it … the power consumes very little, it is quiet, you will always have synchronized backups from your PC. imho