In terms of simplicity, cloud storage is your best bet. Yes it just means you're passing off the task of maintaining the data to someone else. But if you choose a decent provider, they're assiduous with backups. They'll also upgrade their storage over time, basically doing the same thing as buying a new (larger) HDD and copying all your data over to it. Don't think of it as offloading these tasks onto someone else. Think of it as pooling your resources with other people who want to archive data, and hiring someone whose sole job is to do it for everyone.
For larger files (like movies) stored on HDDs, you may want to store them as Parchives (parity archives). That breaks the file up into lots of smaller files, then creates additional parity files. If you break it into 100 files, and add 20 parity files, then up to 20 individual files can become corrupt before the original file becomes unrecoverable. If you keep it as a single large file, then a single bit error will corrupt the entire file.
https://en.wikipedia.org/wiki/Parchive
It won't help if the entire drive dies. But it will help protect against bit rot (bit flips due to cosmic rays, or magnetic strength deteriorating) corrupting an entire large file. (CDs and DVDs have a ton of this type of redundancy built into their encoding layer, which is why you can scratch a disc and it'll still work file. The extra parity info that's written is sufficient to recover the data destroyed by the scratch. HDDs also have this type of redundancy at the magnetic level. But Parchives add it at the filesystem level.)
Personally I'd go with copying files every 7-10 years to a new HDD, plus cloud storage of the most important files. That's pretty much what I do. I've got some 20,000 photos stored on my NAS. I back that up to an external HDD array once a month. Every 7-10 years I replace all the NAS drives with new ones. The NAS runs FreeNAS, which uses ZFS. ZFS has its own file protections. In addition to RAID-5-like redundancy, it also scans all files once a month to check for bit rot. If it detects a file has changed, it "heals" the damage by recovering the original file from the parity data.
The most important files are also backed up to cloud storage (I got 50 GB free for signing up with Box when they first started out). This is to protect me in case my house burns down. I want to set up a similar NAS at my sister's house, and have both of them back each other up. But thus far I've been unable to convince her she needs a NAS. :lol:
■Google gives you 15 GB of cloud storage for free. But you get unlimited storage of photos up to 2048x2048 in resolution. You also get unlimited storage of videos, but I don't know their current restrictions. It used to be videos up to 1080p and 15 minutes length. But I can't find a statement from Google saying what their current limits are.
■If you subscribe to Amazon Prime, it includes unlimited cloud storage of photos of any size via Prime Photos.
■If you subscribe to Office 365, it includes 1 TB of cloud storage on OneDrive.
Also make sure you verify files after you copy them to your archival media. Easy to do with CDs/DVDs (most burning software has an option to verify after the burn). But with HDDs, the default Windows copier doesn't support verify anymore. You need to use a different file copier. I use an older version of Teracopy (v 2.27; version 3.x had problems handling copies of tens of thousands of files). But there are lots of alternate file copiers which support verify after write. In Unix you can use rsync to verify that the copy matches the original.
Doug Lassiter :
Yes on periodic refresh. I have no problem "touching" them occasionally. But always onto new media? As in, chuck my 128GB USB drive and get a new one every decade?? That seems kinda silly.
128 GB sounds like a flash drive, not a HDD. Flash memory stores info by trapping a charge inside a cell. The voltage of that charge tells it whether you've stored a 0 or a 1 in the cell.
That charge slowly leaks out over time. It'll probably last a few years, but I doubt it'll last a decade. If you're using flash media for backup, I'd recommend refreshing it every year just to be safe. Completely copy everything off the flash drive, then write it all back.
Doug Lassiter :
Yes, I know the claim about M-disks being 100% guaranteed.
But until we actually reach that time span...it is simply a prediction.
The better optical media (CDs and DVDs) are known to survive 10-15 years. M-DIscs perform substantially better than those in accelerated aging tests. They basically took the two primary failure modes of regular CD/DVDs, and eliminated them. (The write layer the laser burns holes into normally degrades over time due to oxidation. M-Disc uses a material which doesn't oxidize. The reflective layer can also lose reflectivity or separate/flake off with time. M-Disc doesn't have a reflective layer.)