I have very little experience with linux, so maybe this is a dumb question :)
I run Ubuntu 24.04 on a machine, and I had an old HDD in a usb-case which I mounted using fstab. Worked fine, but I decided it wasn’t appropriate for my purpose and removed it (physically and from fstab).
But it still shows up in the file manager? What am I missing?
Yes, and every single time, it was because filesystems have ways to recover when things go wrong.
But make no mistake, things went wrong. Every time. Even if no files were damaged, the next system accessing the volume would run into a file system that wasn’t exited properly.
And while “never do it while it’s being accessed” improves your chances, due to write caching you can’t actually know if the medium is still writing or reading. Or internally in the middle of a process organising data structures. Or being checked for damage by a background process because the filesystem was flagged for repair due to inconsistencies. Or in the case of spinning rust, in the middle of a background defrag. Or in the case of flash storage in the middle of a trim.
If you have a forgiving boss you could tell him “removed you” to his face every morning… But why would you? Maybe one morning he’ll be cranky, and that one time he’ll take offence and actually fire you.
Point made :D