What’s the weirdest thing one can raid together these days? Maybe a bunch of raspberry pi picos?
Years ago, some colleagues and I did the napkin math over lunch to estimate what a single hard drive would look like that could store all of Google's data. This was for a humorous internal talk. The linear speeds of the outer sectors were enough to leave the solar system (not just higher than Earth's escape velocity). Good laughs were had, I think.
Also on wired: https://www.wired.com/2005/02/ipod-shuffles-m/
[1]: https://wrightthisway.com/index.php/2005/02/03/ipod_shuffle_...
"With Seagate Direct Tape Access, users see the tape device as a logical drive letter from within Windows 95 Explorer, Windows 3.x File Manager, or any other Windows application, similar to a hard drive or CD-ROM. Files and directories can be moved to and from the tape device with drag-and-drop operations."
https://www.eetimes.com/seagate-software-ships-powerful-new-...
... from a time when new software was better than old software.
I had a netbook with an irritatingly slow (and a bit small) eMMC drive for its main storage. I had a pair of microSD cards lying around that were faster for many IO patterns, so I bought a third and strung the three together in mini-USB readers (like https://www.amazon.co.uk/dp/B001JPPQS6/) and run Linux off that using its 3-drive RAID10 support. Leaving a bit of space on each for a smaller RAID1 array for /boot (booting direct form RAID10 didn't work), IIRC the 3x8Gb SD cards give a small touch under 12GiB, larger than the built-in 8Gb, and it was significantly faster (more so than I expected). The slow eMMC got used as backup storage, syncing copies of bits from /home and config from elsewhere, so I could rebuild easily should two cards die at the same time.
The main problem with this arrangement was that is consumed all three of the USB ports, if I wanted to access another drive locally rather than over wireless I'd have to shut down and reboot with at least one of the drives hung off a small USB hub. For some reason it didn't work with one of the drives in the built-in SD reader (the arrays would always start in a degraded state on boot) which I never got around to looking into working around (perhaps a kernel module was missing from initrd that was needed to be able to access the hardware?).
I experimented with RAID5 and RAID0 also. 5 gave a bit more space but was a lot slower for write operations, at least in artificial benchmarks, I assume due to read-before-write issues and the machine having little RAM spare for cache that might mitigate this. 0 did not give notable read performance benefits (though measurably faster writes, and obviously gave much more space), perhaps all the ports running of a single internal USB2 hub was a limiting factor.
By the way, if you want to play with ZFS, it supports using flat files as backing "devices" naturally, so you don't even need to fake a drive using loop devices.
https://fitzcarraldoblog.wordpress.com/2019/10/17/creating-a...
https://askubuntu.com/questions/85977/how-do-i-create-a-file... should, I think, work on any Unix-like system.
On the Mac, create .dmg files for extra convenience.