I have done it with usb floppy drives under openbsd, I am sure it is just as trivial under linux but I had obsd and a bunch of usb floppy drives at my disposal.
#it has been a few years I don't remember if it works with bare drives or if you need a disklabel on each floppy
bioctl -c 5 -l /dev/sd2c,/dev/sd3c,/dev/sd4c softraid0
#the raid will show up now, check dmesg
disklabel -E sd5
newfs /dev/sd5a
mount /dev/sd5a /mnt/floppy/
umount /mnt/floppy
bioctl -d sd5
#after inserting all floppies reassemble the raid
bioctl -c 5 -l /dev/sd2c,/dev/sd3c,/dev/sd4c softraid0
mount /dev/sd5a /mnt/floppy
I love it when a system like this A. does not try to railroad you into the "correct path" and B. the independent layers actually work independently.
One day in what was probably sullen resentment that openbsd has no equivalent to DRBD I assembled a raid on iscsi drives, that is, initiate 5 iscsi sessions to independent hosts then assemble a raid with them. and you can imagine my surprise when it very nearly worked, I could read and write just fine. The part that did not work was drive failure. My guess is that iscsid did not fail a drive in a way that softraid understood. so a drive failure just lead to everything hanging.
Not floppies but I clearly remember some Sun Microsystems video demonstrating ZFS where some guys dressed as over the top engineers randomly disconnecting USB thumb drives that were part of a pool to show the file system resilience.
I thought about trying this with LTO drives, to have a ridiculously slow but also ridiculously high capacity raid, but sadly the LTO tape decks are a bit too expensive for this experiment.
There is a YouTube video on the Action Retro channel, where this article is used as inspiration. Apparently you're not able to use any random floppy drive, but you can use more than five.
Action Retro has a video with floppies: https://youtu.be/1hc52_PWeU8
He also references a MacWorld article with Daniel's array: https://www.macworld.com/article/165663/floppyraid.html
Need to see if someone can hack together RAID on cassettes on an old Apple II
One day in what was probably sullen resentment that openbsd has no equivalent to DRBD I assembled a raid on iscsi drives, that is, initiate 5 iscsi sessions to independent hosts then assemble a raid with them. and you can imagine my surprise when it very nearly worked, I could read and write just fine. The part that did not work was drive failure. My guess is that iscsid did not fail a drive in a way that softraid understood. so a drive failure just lead to everything hanging.
https://www.youtube.com/watch?v=1hc52_PWeU8