I'm installing a new 2TB internal drive at the moment, and want a good backup system for it. The plan is to back up to a 2TB external drive which will be kept off-premises. I'll bring it "home" to the office periodically to "sync" the files from the internal drive.

I'm looking for software that will, in effect, "watch" the internal drive for changes in files and folders, so when I periodically hook up the external drive, it can sync (mirror) the internal drives changes....without copying all the contents with every sync.

I know I have this capability with my HP PC, which I back up faithfully, so I'm assuming that most "backup" software will do this, but there are so many backup software packages available, I'm not sure where to start.

So, I'm starting with you guys: Is there a favorite, or an "old standby" in this category of software? I'm concerned about reliability and even ease of use over cost.
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::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::