The question here seems to be about just how disconnected and geographically distinct a replicated copy of your data needs to be before it's a backup and not high availability/redundancy infrastructure. My gut is that you're close, but still need a backup.
To bring together (cherry-pick) some thoughts in the other answers and comments, you can go really far down the path of "well, X technology doesn't cover Y disaster scenario, so it's not a backup," and at some point you need to decide what's reasonable for you, which seems to be why you're asking. My feeling on this, and I think the feeling of many of the commenters, is that your backup needs to exist on a separate technological infrastructure from your in-use data so that failures, accidents, and malicious actions either can't propagate or have a much higher hurdle to cross. An example given in the comments is someone deleting the volumes, which is a valid, not pie-in-the-sky scenario in my opinion. But additionally, a real-world example from my work. The university I work for (but thankfully don't manage this infrastructure for) has some serious high-availability virtualization infrastructure that supports a lot of the campus facilities. It's at multiple sites, but is all running on one vendor's platform. An obscure bug cropped up one day that caused a failure cascade that first took down a single server, then when the load shifted, it took out the rest of that site, and then when the load shifted again, it took out the other sites hosting that infrastructure. (I believe they've resolved this issue since then). The data wasn't lost in this case, but it's feasible to imagine a scenario involving your data where it was.
You want your backup to be immune to all of that, and even accessible while that infrastructure is down. If the data is unavailable for a week while your RAID rebuilds, being able to recover business critical documents from backup is nice (though not required). If your RAID disappears, then replicates to your other site, you'll really want that backup to be from a separate vendor or on some isolated media like tape.
All this said, I'll again repeat that your backup should be on a separate infrastructure from your data. There are many levels of isolation here, but I think anything connected through direct replication is too close to be a backup. You'll want something in addition.