Hi Andy, Thank you for your comments.
I completely agree that USB storage is not the most reliable solution, and if this were a conventional server I would probably choose a different architecture. The motivation here is a little different. I'm trying to understand how Linux behaves when the target filesystem unexpectedly disappears and how to prevent applications from silently falling back to the underlying filesystem. The USB SSD is simply a convenient and inexpensive way to reproduce that failure mode. The same question could arise with removable SATA devices, SD cards, or other storage that may become unavailable unexpectedly. Several people have suggested placing the log files inside a subdirectory that exists only on the mounted filesystem, which seems like a very elegant safeguard. I'm also interested in exploring whether systemd, udev, or the logging daemon itself offer additional mechanisms for handling these situations gracefully. Thank you again for your observations. -- Marcelo
