I have some USB-attached HDDs connected to a laptop running Debian 12. Recently I had a problem ejecting them using the file manager and the Disks app, something on the drives was still "in use" even when I had closed every open application.
Since then I've learned of the existence of 'lsof', but at the time my experience of Windows and macOS suggested that, under these kinds of circumstances, performing a shutdown will clear the holds on the drives and cleanly eject them during the process. So as I didn't know what else to do I shut down Debian using the menu. The last thing I saw before the laptop powered off was a series of messages reporting that both external drives had failed to unmount cleanly, and this was confirmed by the nasty clunking noise from the drives indicating sudden parking of the drive heads when the USB power was unexpectedly removed. Following this incident I've had to recover some several GBs of files from each drive. Obviously this wasn't a very pleasant experience, so I'd like to know what steps I can take to make Debian act more responsibly in future. IM(H)O part of the problem was that the first thing to get torn down during the shutdown was the GUI, which meant that there was no way for a user to intervene if there was a problem with ejecting the drives cleanly. Windows and macOS will prompt the user using the GUI if there's a problem that means a drive can't be automatically ejected cleanly during a shutdown, giving users an opportunity to abort. Can I modify the Debian shutdown sequence to keep the GUI available until all drives are safely ejected? I'd welcome any other suggestions to make Debian less likely to cause data loss on external drives during shutdown.
