B2: How many times does Duplicati try to get an Upload URL when something goes wrong? commented:
I’m sure hoping there’s not a delay (and plausibly there could be one) where an upload fails, Duplicati tries delete immediately, delete fails because the file’s not there, then the file shows up. B2 isn’t a simple write operation into a file (same might be true for other cloud services though). File needs to be processed first.
B2 Resiliency, Durability and Availability talks about this, and I suspect it all happens AFTER upload ends.
but how quickly the file actually shows up in the normal and failed cases might be hard to determine manually. I suppose with two computers, one could do a slightly throttled large upload, disconnect its Internet connection midway, and refresh B2 UI from another computer to see if anything shows up.
Delete by Duplicati from first computer can’t happen because it’s got no connection, but it might try. Logging would show that. So one could perhaps see it try the delete before B2 put the partial file up, however with most of these cloud services (too lazy to confirm B2) there’s info such as a hash that destination will check to make sure things arrived as intended. If not, I’d expect they’d discard the try.
This all makes me worried again whether the no-look delete is a good idea. I thought I saw deletions handled differently at the end of the backup, based on file listing, i.e. if file isn’t there, don’t try delete.