Got my hands on a Dell Latitude ON module. Turns out it’s nothing more than a 2 GB flash module that fits in a mPCIe slot and is wired to the USB lanes. Shows up as /dev/sdb.
I do have a couple of old laptops that don’t have a secondary SATA drive slot, but do have open mPCIe slots with USB lanes (no mSATA lanes). The Latitude ON module would allow for a dual drive system, albeit a rather crappy one. What would you put on a secondary internal drive if it were limited to 2 GB and USB protocol?
Rescue partition?
maybe a stripped down winxp installation, lol
Back in my day, we had this feature on Windows Vista called ReadyBoost that took advantage of the low-latency of flash media to supplement our slow HDDs. I’m not sure if there was a direct replacement for this in the Linux world. There are filesystems that take advantage of faster tiers of storage, but different latency tier exploitation isn’t something that I know to be readily available.
Today, 2GB of USB flash is next to useless, but I would consider a homebrew rescue system to restore your backups and fix problems without needing to prepare an external flash drive.
A backup drive ? dotfiles (.config) ? /tmp /var/log /boot ? map it into your home for something temporary - Downloads ? Slow audio files ? If you like to tinker for fun: btrfs / bcachefs could perhaps utilize it for something, like automatically offloading unused/slow files to the slow usb ? Raid ? ;) Create a partition and let zram swap compressed unused memory pages to the usb partition (I think it keeps pages compressed now ?). You can also run ‘usb over ethernet’, so another machine can use it directly - not sure why tho ;)
On a side note. I still use one of my first usb 1.? drives with 32mb in my old router. 32mb is still 12mb more than my first hard drive, and it fits well with the small openwrt packages. It even has a little slide button to select ‘floppy drive’ mode and a physical ‘readonly’ mode. I wonder what the smallest/oldest usb stick people still use, are ?