Software to automaticaly sync backup hard drives?

sirhawkeye64

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May 28, 2015
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So, I've got three hard drives: my primary drive (working drive), an on-site backup drive, and an off-site backup drive. I do photography so the contents of the primary/working drive changes almost daily.

What are some good (preferrably free) applications for synchronizing the two backup drives to my primary drive? Basically, I want to be able to select a folder (as my working drive has other stuff on it that doesn't change that much or doesn't need to be backed up), and when I plug in either of the two backup drives, I can click a button and have it automatically sync the drive (backup any new/changed files, but also remove any files from the backup drive that I may have deleted from my primary/working drive).

Suggestions? I thought there was a program called SyncBack (and it was free....?)