I don't use Backblaze, but I suspect from the above comments that the client does not even display some kind of warning saying, "Hey, you haven't connected this drive for X months. We just wanted to let you know that this data will be deleted from our systems in Y days. Please connect the drive to make sure we retain the data." and then proceed to display this warning periodically a few times, like a countdown (but not annoying enough to be shown on every run of the client). This kind of warning would be my suggestion to the Backblaze team. This becomes more important with SSD based machines that generally have a lot lesser storage than before while people are taking a lot more pictures and videos and resorting to storing them in cheaper (per GB) external HDDs (at least the people who do like to have a local copy).
Yev from Backblaze here -> If we detect a missing drive we send a warning email at the 14-day, 21-day, and 28-day mark to remind folks to plug them in - or create a restore if they no longer have the drives. If they still don't plug in the drive after those days, then the backup does get removed, but we do try to warn them ahead of time!
I _Believe_ the client displays this information, buy I could be wrong about that. I know I get a few helpful emails, starting with a couple weeks notice though.
