Backing up to B2 storage. I notice if I move a source directory its entire contents will be re-sent/backed up again. Is there any hope for a mechanism by which moved but unmodified files can simply be moved on Backblaze's end without re-sending?
That's not currently possible. Objects in the cloud generally cannot be moved as they are write-once. You would have to perform a cloud copy and a delete for the objects in the cloud that moved locally - which is not something we support.
Are you using the new backup format? The new backup format includes client-side deduplication which would prevent the need to send all the matching file data a second time.
Ok. I did not realize you were on Linux. If you move a file locally, it will look like a file delete and new file create to the OS and to our software. What happens with the locally "deleted" files in backup storage depends on the retention settings for your backup plan. If you have questions, please post what you are using and I'll be happy to review.