Forgot to mention one detail. I copy from server to Data Domain, so the server's NIC is a GB NIC, and I'm slowed by the network link from those servers to the Data Domain location, which is 1/2 mile away at another building. That is definitely something to consider.

I think mine is a fibre link, so I'm probably not losing that much, it is actually pretty quick.

But, I would think I would have a tough time with a 1TB file!

I mitigate my large backups by backing up to the owning server, then copying to the Data Domain. You could go directly to the Data Domain if it was so big you don't have the room to go first to the server. Going directly would then definitely be restricted by the network link speed.

You could do Full backups once a week, with nightly incrementals, that would make it faster, unless a large percentage of the records are modified (directly, with page-splits, etc.).