External DVD/CD

[ab1jx]

I was so impressed by the MTBF figure of 180 years on my Intel nvme SSD that I bought another of the biggest size I could get (2 TB).  I put the 2nd one in a USB adapter, might collect a couple more.  It's possible for some program to erase them but other than that I figure it'll last my lifetiime.  This isn't offline storage, it doesn't actually get it out of the way.  But in an external unplugged USB adapter it almost is.  I put a few spinning rust hard drives into them too, if they aren't plugged in they aren't spun up and wearing out.

The ones that hold 3.5 inch drives have power supplies, the ones with laptop drives or nvme are USB-powered.  A 3.5 inch can go up to 10 TB I think, maybe more. I have a 2 TB laptop drive in one, but the PBP doesn't supply enough power to run it, it needs a powered hub.

[Arwen]

In reality, my "important data" is less than 4.7GBytes so I probably could have gotten away with single layer DVD M-Discs.

I haven't looked, do those come in rewriteable?  A multi-session burn will let you keep using parts of it each time, so you could have versioning even without being rewriteable.  You sacrifice a little capacity for that.

The M-Disc BURN data in to non-organic materiel, thus are not re-writable. That is the whole intent, make it very hard to flip bits after a burn.

I don't know if they can be appended to, using multi-session.

My usage of them is archival storage. Burn once, file away.

[ab1jx]

I once did a quick price comparison and just buying hard drives compared well with removables.  2 TB is around $55 https://www.google.com/search?psb=1&tbm=...kFegQIARAS  3.5 inch goes a little bigger and cheaper per terabyte.  I think the internet archive (archive.org aka the wayback machine) found it was most cost-effective, or did years ago.  2 TB seems to be the max size of a laptop (2.5 inch) hard drive.

You can get 2 TB of nvme SSD for around $225. https://www.google.com/search?psb=1&tbm=...kFegQIARAS

But yeah, there's at least a theoretical advantage to mostly indestructible offline storage.  And if 1 fails most of them are probably OK.  2 TB is 465 DVDs.  I was buying them on sale at Staples, Sony only, for $20/100 pack around 2009, so that was $93 for 2 TB.  And 465 DVDs is a lot of plastic.  I see advantages to both methods.
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I just wrote this and tested it.  apt-get install par2, then save this as something and chmod +x it.

Code:

#!/bin/bash
# Makes par2 files for all files in a dir with extension on cmd line
# Use like parall doc, or parall jpg (no period)
shopt -s nullglob
for f in *.$1
do
/usr/bin/nice -n19 par2 create -r10 $f
done
# make a pars dir and put all the clutter in there - copy back to use
mkdir -p pars
mv *.par2 pars

Par2 files provide redundancy and work a little like a RAID.  If some portion of your material goes bad, you can recover by having enough par files.  Read the part2 man page after you install it, this is set for 10% redundancy, you might want more like 30-40%.  They take up space but they're like insurance.  I wrote this for making par files for directories full of mkv files but you could use it on any file type. This makes a set of par files for each mkv file because they're each 300 mb or so, you could easily make a set for a directory full of mixed files. Filenames are based on the input file names so nothing gets clobbered.