Is Duplicati robuust under unmounting target disk as backup is running?

Suppose Duplicati is running a backup process and while that process is running the user unmounts the external disk on which the backup resides. Is Duplicati robust under that circumstance? (I suspect not now that I have a damaged/unrecoverable backup possibly from that scenario).

Duplicati should handle this without “blowing up”, however on the next run it will likely give a warning (I think, not an error) about unfinished files. If the upload file is partially written when the dismount happens then on the next run you might get something like a “check SHA” error (as in the backup will stop) - though I’m not sure that scenario would actually happen.

Other than that, it should pick up right where it left off.

So my apparently damaged-beyond-repair backup (see other thread) doesn’t come from that? Having to do that backup all over again with the entire backup lost doesn’t make me feel very good about the robustness of Duplicati.

The problem is not that the backup was damaged, but it could not be fund and Duplicati did play a role in it. I’ll start a new thread.

If your source computer is a Mac and the backup job ran initially when the USB drive was attached, then again when it as NOT attached, you may be running into this:

I’ve marked this as a solution before actually trying it out. Note that this has nothing to do with USB (in my case the drive is a Firewire drive). I’ll ask a followup question in that thread.

Understood. I suspect the --alternate-destination-marker might actually be usable with any not-always-available destination…