I have two WD 4TB external USB drives after I outgrew my last 2TB. I got two to make a back up of one after a friends drive crashed and fear of it happening to me. Drive 1 is an HGST Touro 4TB (WD internal drive) - love the case but is extremely slow I guess with seeking? Takes a while load up quite often and is very irritating. Drive 2 is a WD 4TB MyBook that I haven't used yet besides to test with different programs for DOA.

Basically what I want to do is mirror Drive 1 onto Drive 2, and have it overwrite any changes I make, weekly-ish or how ever often I set the schedule, to Drive 2 (similar to when you make an on-the-go playlist on your ipod it copies it to itunes). I have tried a few programs just using test folders on my desktop and haven't liked the format or the extra folders they created. I want an exact mirror, and the ability to flip if I find out that Drive 2 is quicker for daily use (I use Drive 1 daily as a storage unit for all important data, movies, files, docs; not just as a backup device an stays powered up 24/7 due to no power button and only gets unplugged if I go on vacation)

What do you guys/girls all use and what are the pros/cons? Thanks in advance!