To me, it is important to know what I need/expect and classify accordingly: Am I looking for
- access speed
- archive quality
- temporary/short term storage
- size of data
- etc. ??
But what is most important is to decide which data can be lost (but then.. why (spend money/effort to) save it?) and which data we really actually want to save..
Most solutions have their problems:
- Generic writable optical media (organic dye degrades over time, bit-rot, no guarantee you retrieve what you stored)
- Conventional hd (can break, bit-rot (although, interestingly, numerous data-recovery experts state they've never seen actual bit-rot and the advent of ZFS later proved 'bitrot' on HD's usually was faulty data from (s)ata/ide controllers and bit-rot in memory))
- Tape (somewhat less 'conventional' to an average user, bitrot, more constrained storage requirements)
- Flash (more expensive compared to generic writable optical media, bit-rot)
- Cloud (privacy, even a monetary consolation 'prize' when they loose your child-hood video's just doesn't compensate the loss)
All above need some form of error-checking (to verify if you got what you stored).
Often people duplicate the media completely (which doubles cost, and still leaves headaches once one tries to restore). Sometimes people add parity files as well (bloating size).
All of this is just hassle (especially with very large files) and extra cost and ideally we'd like to avoid that.
In my current opinion, that leaves just 2 solutions (for long(er) term data storage where we try to actually retrieve the data exactly as we once stored it:
- Home-Fileserver running ZFS (file system) cluster on a 64bit machine with ECC support and at least 8GiB ECC Memory (2 disk spares).
Con: growing your pool is a bitch/impossible (depending on implementation), price (as you start with as much overcapacity as you can afford, also talking about spares and future identical replacements). Can't (cheaply) store duplicate in relative/friend's home.
Pro: fast access-time (over network), safe against bitrot; as long as your set works you got what you stored, no excuses.
- M-Disc (available in DVD 4.7, BD-R 25, BD-R 50 and BD XL 100)
Con: slower access (and you need some indexing software). Requires a working drive (in the future)
Price per disk drops when you realize you don't need to copy your archives every x-years and don't require duplicates (compared to conventional optical media)
Pro: safe against bitrot, you get what you verified after you burned it, no excuses for >lifetime. Cheaper to start: get M-disc compatible drive (archival quality optional), enclose in decent usb-3 enclosure, store with disks and buy the discs. Also, compared to the zfs file-server, this does what most of the people envisioned they were doing when they en-masse transferring their childhood video's to DVD (and tossing the degrading original tapes). Finally, no virus can modify the data after storage... Price-efficient to store a duplicate at a friend/relative's home
Your current 2TB could fit on just 20 BD XL 100 discs...
No solutions (sadly) are 'for-ever' not even 'our life-time' (due to evolution in devices and their interfaces). At some point one will transfer the M-disc's to a medium more appropriate to the time, make no illusions about that. However, the beauty is that once the time comes that we know almost nobody has an USB3 port anymore (and almost no converters and/or BD Drives) and we decide to migrate our data to another medium, we still get the data we once stored! Besides, it is not unreasonable that a specialized digital archival/forensic lab in the future will still have a specialized optical drive to recover data with..
Personally I think M-Disk can give a time-span of 20 to 25 years (specifically: before it is no longer reasonably possible to obtain a PC with USB3 Compatible (adapter) interface and (external) BD Drive secondhand without paying ludicrous prices)
Just my 2 cents