How can I prevent Backblaze from frequently (every few days) reuploading my entire external hard drives?

Question

It seems that Backblaze is frequently (every few days) reuploading my entire external hard drives. Backblaze already has the files on its server, so it's only scanning my entire external hard drives, get some checksum of each file, compare against the files on its server and then skipping the files. But that still means reading and computing the checksum of many TBs of files every few days, which I don't want. I still want Backblaze to upload new or changes files.

How can I prevent Backblaze from frequently (every few days) reuploading my entire external hard drives? I use Backblaze on Windows 10.

Answer 1

Blackblaze only uploads the checksums of the files, not the files themselves, for the entire partition. The checksums are calculated locally by the application.

If this is still too much, you may restrict further the Blackblaze backup operation by running its application (usually resident in the traybar) and entering Settings.

In the Schedule tab, you can set the schedule to Continuously, Once Per Day or Only when I click BackupNOW. The last option will stop all backups until you decide to permit them again.

Answer 2

Here is one event that triggers re-queue of all data on a drive, explained by Backblaze employee clunkclunk:

Since the drive was deselected then reselected for backup, Backblaze has re-queued all the data on that drive. As each file comes up in the queue, it's checksummed to see if it's already been backed up, and if it has, it's just noted in the logs and not backed up again. We call that process "de-duplication."