I’ve been using Backblaze for offsite backup for about a decade. Overall, I recommend the service.

But a few months ago, I got an alert from my Backblaze client that my bzfileids.dat had become too large, and the only remedy was to completely remove my backup and start over.

The issue wasn’t how much data I was backing up—that’s unlimited—but the number of files or top‑level directories. Backblaze uses bzfileids.dat to track every backed-up file, and if it becomes too large (the limit is typically hit around 200,000 entries), the client fails and often requires you to delete the existing backup and start fresh.

I do back up a lot of data—nearly one million files. Re-uploading the entire backup took about a month since it uploads at a slow trickle and, during that time, new projects weren’t being backed up offsite, which is uncomfortable.

I do have local backups, but I consider offsite backup critical. I couldn’t find a way to check when a limit might be reached, and no warnings are given—just a notice that your backup is gone.